The Mining Magazine
M anaging Director and E ditor : W. F. W h i t e . A ssistants : St. J. R. C. S h e p h e r d , A.R.S.M ., D .I.C ., F.G.S. ; F. H i g h a m , A .R .S.M ., M .Sc., F.G.S.
P u b l i s h e d on th e 1 5 th o f e a c h m o n th b y M i n i n g P u b l i c a t i o n s , L i m i t e d , a t S a l i s b u r y H o u s e , L o n d o n , E.C. 2.
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Vol. XLI1. No. 3. L O N D O N , M A R C H , 1930.
P R I C E O N E S H IL L I N GC O N T E N T S
P A G E
Ed it o r ia l
N otes ... 130
Telephone N u m b e r; A J o in t Geological Survey for Kenya, U ganda an d T an g an y ik a T e rrito ry ; B ritish Industries F a ir ; Incom e Tax A uthorities R ebuked ; The D ouglas Medal aw arded to D r. J . V . N . D o rr ; In stitu tio n Gold M edal aw arded to S ir Thom as H olland ; T he E m p ire Congress. M e t a l l u r g i c a l a n d C h em ical E n g i n e e r i n g ... 130
T he p ap e r p resen ted a t th e F eb ru ary m eeting of the In stitu tio n is review ed. A n o th er C hange ... 131
The proposal to move th e h ead q u arters of the In stitu tio n is exam ined. T he In d ia n B u d g e t ... 132
A ttention is directed to p o in ts affecting m ining industries in the new In d ian B u d g et. A Q u estio n of E t h i c s ... 133
The em ploym ent of engineers to re-open confiscated properties in R ussia is discussed. Re v ie w o f Mi n i n g... 13 4 Ar t ic l e s M illing P ra c tic e a t F resnillo R . R . B y le r 13 7 The au th o r, who is m etallurgist to th e Fresnillo C ompany, describes th e practice on this silver-lead-zinc pro p erty , which is situ a ted in th e S ta te of Zacatecas, Mexico. New S eism ograph for G eophysical S u rv e y ... D r. A . 0 . R a n k in e 147 T h e T in D ep o sits of G unong B a k a u D r. F . T . In g h a m 1 51 The au th o r gives an account of the lode-tin deposits on Gunong B akau a t the in ter-state b o u n d ary between Selangor and P ahang, based on recent observations. Bo o k Re v i e w s N aish and Clennell’s " Select Methods of M etallurgical A n alysis ” , W. A . C. Newman 157 B ritton's " H y d ro g en Io n s: T heir D eter m ination and Im portance in Pure and Industrial C hem istry ” D r. H . J . T . Ellingham 157 W ills’ " The Physiographical E volution of B ritain ” ... D r. C. J . Stubblefield 158 Ne w s Le t t e r s Jo h a n n e s b u rg ... 159
M ineral O u tp u t for 19L;9 ; Alluvial D iam ond Slum p ; A nother P latin u m Producing Mine ; T ransvaal and Swaziland Asbestos ; A Manganese Ore S hipm ent ; New Manganese Field ; T ransvaal E m eralds ; A Kieselguhr Deposit. P A G E B r i s b a n e ... 160
T he Coal Crisis ; M ount Isa A ctivities ; The W hitw orth C o m p a n y ; C loncurry Copper Ore ; The Bendigo Goldfield ; B roken H ill S tatistics. V a n c o u v e r ... 162
A Com pany F ailu re ; “ W hite B ulletin ” : N oble Five Mines ; P rem ier B order ; E x p o rts of C oncentrates ; Sm elter Fum e. T o r o n to ... 164
B rokerage F rau d s ; Coal in O ntario ; Sudbury D istrict ; Porcupine ; K irkland ; P atricia D is tr ic t; M anitoba. C a m b o r n e ... 166
The Price of T in ; Cornish R estriction ; Labour ; P ros pecting ; C astle-an-D inas; Lam briggan ; D olcoath. Pe r s o n a l ... 167
Tr a d e Pa r a g r a p h s... 167
B ritish Industries F a i r ... 168
Me t a l Ma r k e t s... 171
St a t is t i c s o f Pr o d u c t i o n... 173
Pr ic e s o f Ch e m ic a l s ... 175
Sh a r e Qu o t a t io n s ... 176
Mi n i n g Dig e s t The Production of R adium and Vanadium from Carnotite ...H . A . Doerner 177 The G eology of N orthern R hodesia (con cluded from th e February issu e, p. 117) / . A . Bancroft and R . A . Pelletier 180 R ecent D evelop m en ts in th e R ecovery of Mercury ... L . H . Duschak 182 Chromium... L . A . Sm ith 187 Copper, Lead and Zinc M ining Production in th e U n ited S tates ... 188
Centrifugal Concentration . . H. A . Doerner 189 S tatistics of Lead Production L . A . Smith 189 Flow of G ases through B eds of Broken Solids C. C. Furnas 190 Sh o r t No t i c e s... 190
Re c e n t Pa t e n t s Pu b l i s h e d... 191
Ne w Bo o k s, Pa m p h l e t s, e t c... 191
Co m p a n y Re p o r t s... 192
Lower Bisichi (Nigeria) Tin Mines ; Penaw at (Malaya) Tin D redging. Di v i d e n d s De c l a r e d... 192
Ne w Co m p a n i e s Re g i s t e r e d ... 192
3— 4 129
E D IT O R IA L
T
H E te le p h o n e n u m b e r of th is office, w h ich is also t h a t of th e T e c h n ic a l B oo k sh o p , h a s b een c h a n g e d to M e tro p o lita n 8938.T
H E D ire c to r of th e G eological S u rv e y of U g a n d a is n ow v isitin g K e n y a for th e p u rp o se of m a k in g a p re lim in a ry su rv e y in S o u th e rn K a v iro n d o a n d discu ssin g w ith th e K e n y a G o v e rn m e n t th e in a u g u ra tio n of a jo in t G eological S u rv e y for K e n y a , U g a n d a , a n d T a n g a n y ik a T e rrito ry .T
H E B r itis h I n d u s tr ie s F a ir , w h ich is re fe rre d to in som e d e ta il elsew here in th is issue, w as h e ld s im u lta n e o u sly in L o n d o n a n d in B irm in g h a m . T h is m a rk s th e e le v e n th y e a r of th is successful a id to B ritis h tr a d e w h ich , s ta r t e d in 1920, h a s ste a d ily in c re a se d in size a n d im p o rta n c e w ith ea c h succeeding y e a rR
E C E N T L Y th e legal ad v isers of th e Crown h a v e b e e n s h a rp ly c riticiz ed b y L o rd D u n e d in , d u rin g th e h ea rin g , in th e H o u se of L o rd s, of a n in c o m e -ta x a p p e a l con cern in g th e B u r m a C o rp o ratio n . J u d g m e n t w as a g a in s t th e C row n, a n d L o rd D u n e d in m a d e th e o b se rv a tio n t h a t it w as h ig h tim e t h a t th o s e w ho a d v ise d th e Crow n sh o u ld m a k e u p th e ir m in d s t h a t th e Crow n m ig h t be w rong. S u ch a w a rn in g sh o u ld serv e as a ch eck to th o se re sp o n sib le for th e ap p e al, for th e ir use of th e p o w er to p r o tra c t litig a tio n seem s to b e exercised all to o freely.services to geological science a n d to the m in e ra l in d u strie s d u rin g h is te n u re of high p u b lic a p p o in tm e n ts — n o ta b ly th o se of D ire c to r of th e G eological S u rv e y of In d ia a n d of R e c to r of th e Im p e ria l College of S cience a n d T e c h n o lo g y — a n d of his re
search es a n d p u b lic a tio n s u p o n th e m ineral reso u rces of th e B ritis h E m p ire a n d their re la tio n s h ip to n a tio n a l a n d in te rn a tio n a l p ro b le m s.” T h e m e d a l w ill b e p re se n te d a t th e A n n u a l G en eral M e e tin g on J u n e 26.
T
H E T h ird E m p ire M ining a n d M etallu rg ic al C ongress is on th e eve of its opening. D e le g a te s fro m th is country, rein fo rced b y som e fro m C a n a d a a n d the U n ite d S ta te s, sa ile d fro m S o u th am p to n in th e K e n ilw o rth C astle on M arch 7.
In c lu d e d in th e p a r t y w e re D r. Charles C am sell, D e p u ty M in ister of Mines for C a n a d a , a n d Mr. T . W . G ibson, D eputy M in ister of M ines for O n ta rio . D r. W illiam C ullen a n d Mr. F r a n k M erricks travelled as th e official re p re s e n ta tiv e s of th e In s titu tio n on th e E m p ire C ouncil, th e m ain bu sin e ss of w h ic h w ill b e th e c o n tin u a
tio n of th e d iscu ssio n of S ir Thom as H o lla n d ’s p ro p o sals fo r th e co-ordination of m in e ra l reso u rces. I t w ill b e recalled t h a t Mr. C harles M cD erm id , w ho is also tr a v e llin g w ith th e d eleg a tes, w as recently in N ew Y o rk d isc u ssin g th is su b je c t with th e A m eric an I n s t i t u t e of M ining and M e tallu rg ica l E n g in e ers.
T
H E a w a rd of th e J a m e s D o u g las M edal to D r. J . V. N. D o rr b y th e A m eric an I n s titu t e of M ining a n d M e tallu rg ica l E n g in e ers, for h is a c h ie v e m e n ts in th e d e v e lo p m e n t of h y d ro -m e ta llu rg ic a l p la n t a n d p ra c tic e , w as a n n o u n c e d in th e M a g a z i n e for J a n u a r y la s t. I n ac c e p tin g th e aw a rd , on F e b r u a r y 19, fro m th e h a n d s of Mr. F . W . B ra d le y , th e re tirin g P re s id e n t of th e I n s titu te , D r. D o rr p a id gracio u s tr ib u te to th o se w ho h a d c o n trib u te d to h is success— h is a sso cia te s a n d th o se pro fessio n al m e n w hose c o rd ia l c o -o p e ra tio n h a d b ee n so re a d ily fo rth c o m in g .
T
H E G old M edal of th e I n s titu tio n of M ining a n d M e ta llu rg y h a s b een a w a rd e d to S ir T h o m a s H . H o lla n d , K .C .S .I., K .C .I.E ., V ice-C h an cello r of th e U n iv e rs ity of E d in b u rg h , “ in rec o g n itio n of h is e m in e n tM e ta llu r g y a n d C h e m ic a l E n g in eerin g A n in te r e s tin g d isc u ssio n follow ed the re a d in g of a p a p e r b y D r. W . E . Gibbs, pro fesso r of ch e m ic a l e n g in ee rin g in London U n iv e rsity , e n title d “ T h e R o le of Chemical E n g in e e rin g in M ining a n d M e tallu rg y ,”
a t th e F e b r u a r y m e e tin g of th e In s titu tio n . B efore co n sid e rin g th e s u b je c t of th e paper it is as w ell to re m a rk a t th e o u tse t, as D r. S y d n e y S m ith e m p h a siz e d in his con
tr ib u tio n to th e d isc u ssio n , t h a t th e title is m islea d in g . A n a l te r n a tiv e suggested b y D r. S m ith , “ C om m on F a c to rs in Chemical a n d M e tallu rg ica l E n g in e e rin g ,” w o u ld have b e e n m o re su ita b le , a lth o u g h e v e n this w o u ld p ro b a b ly h a v e le d m e ta llu rg ic a l en g in ee rs to e x p e c t m o re fro m th e paper th a n it a c tu a lly possesses. I n h is paper P ro fesso r G ibbs a n a ly se s th e functions a n d scope of th e p ro fe ssio n w h ich h a s come to b e k n o w n as c h e m ic a l en g in ee rin g , a 130
d ev e lo p m e n t of c h e m is try cum en gineering w hich h a s re su lte d from ex p lo ra tio n in th e b o rd e rla n d sciences of p h y sic al ch e m istry a n d chem ical physics. T h is tr a in of th o u g h t suggested to th e a u t h o r ’s m in d analogies b etw een th is su b je c t a n d t h a t w hich h as long been know n as m e ta llu rg ic a l engineering.
T hus th e re are in m o d e rn ch e m ic al in d u s try m a n y processes, su c h as cru sh in g , filtra tio n , se d im e n tatio n , c ry sta lliz a tio n , e v a p o ra tio n , drying, a n d d is tilla tio n — to m e n tio n a few a t ra n d o m — w h ich a re com m on to th e tw o an d he feels t h a t in v ir tu e of th is k in sh ip th ere sh o u ld be a closer liaison b etw e en chem ical engineers a n d m e ta llu rg ists. T his is th e su b sta n c e of th e p a p e r, w hich concludes w ith a specific p le a for ex ch an g e of in fo rm a tion b etw een th e te c h n ic a l societies concerned and for research c o -o p e ra tio n b etw e en th e se societies a n d p la n t m a n u fa c tu re rs. T h e rem ainder of th e p a p e r is ta k e n u p w ith extensive exem p lificatio n of th e v ario u s p oints raised a n d for th is reaso n it m a k es good rea d in g for th e s tu d e n t o r a n y o n e w ith no p rev io u s e x a c t know ledge of th e sciences involved.
A ny p ro p o sal for th e pooling of in fo rm a tion presu p p o ses t h a t th e b en e fits of su c h an interchange sh a ll be m u tu a l, b u t it is difficult to see w h a t benefit th e re is for m e tallu rg ica l engineers in a n y closer conference w ith th e ir chem ical in d u s try cousins th a n is p ro v id e d for a t p re se n t. On th e o th e r h a n d , h a v in g regard to th e pio n eer p o sitio n of m e ta llu rg y in th is m a tte r, th e re is, p erh a p s, som e reason for su p p o sin g t h a t ch e m ists engaged in th e w orking o u t of n o n -m e ta llic in d u s tria l processes m a y find som e g u id a n ce in th e m e ta llu rg ist’s te c h n iq u e . A s P ro fesso r L aw n p ertin e n tly rem in d e d th e a u th o r, how ever, a n o th er co n sid eratio n arises. A n essen tial difference b etw e en a m e ta llu rg ic a l a n d a n o n -m etallu rg ical process is to be fo u n d in th e fact t h a t in th e fo rm er th e co m m ercial asset consists in th e m in e ra l dep o sit, w hile in th e la tte r it resides in th e process itself.
T here is th u s ev e ry reason for m e ta llu rg ists to be open as to th e m e th o d s w hich th e y em ploy, as it is b y su c h free exch an g e of experience t h a t im p ro v e m e n t is m a d e a n d e x tra c tio n efficiency increased . T h e chem ical engineer, on th e o th e r h a n d , is d e p e n d e n t on th e process itself for com m ercial success a n d c a n n o t, th erefo re, afford to disclose a n y d eta ils of his o p era tio n s. As D r. S ydney S m ith in sisted , th e ch em ist in in d u s try owes a considerable d e b t to his b ro th e r te ch n ic ia n th e m e ta llu rg ist a n d will co n tin u e to do so.
T h e re is y e t a n o th e r asp e c t of th is m a tte r to w hich a tte n tio n m a y w ith a d v a n ta g e b e d irec ted . I n re m a rk in g in th e se colum ns on D r. C ullen’s re c e n t p a p e r on th e fu tu re p o sitio n of n o n -ferro u s m e ta llu rg y in G re a t B rita in , in F e b ru a ry , 1929, c o n sid eratio n w as in v ite d of th e d e s ira b ility of div id in g m e ta llu rg y in to tw o p a r ts co n v e n ie n tly called M etallu rg y I a n d M e tallu rg y I I, th e first-n a m e d covering th e e x tra c tio n of m e ta ls from th e ir ores, in c lu d in g all th e p rio r processes of c o n c e n tra tio n , a n d th e second th e a fte r-tr e a tm e n t of th e se m e tals, in c lu d in g alloying, h e a t tr e a tm e n t, a n d m e ch a n ica l w orking. A d m ittin g th is sub-d iv isio n , it is possible to agree w ith th e a u th o r of th e p a p e r now u n d e r review , t h a t th e re is som e com m on g ro u n d b etw e en M etallu rg y I I a n d chem ical engineering.
I n fac t, b o th sciences a re co n cern ed w ith th e in d u s tria l e x p lo ita tio n of ra w m a te ria ls.
A n o th e r C h a n g e
I n M ay, 1921, w hen th e I n s titu tio n of M ining a n d M etallu rg y decided to m ig ra te from F in s b u ry Circus to C leveland H ouse, C ity R o a d , in referrin g to w h a t w ere a t th e tim e co n sidered to b e th e d raw b ac k s of th e change, th e Ma g a z in e sa id : “ I n a n y case, it is m ore th a n p ro b a b le th a t th e new hom e w ill p ro v e to b e o n ly a te m p o ra ry m a k e s h ift.’’ T h a t th is view w as w a rra n te d is evid en ced b y th e p ro p o sal w hich, as th e re su lt of m u c h n e g o tia tio n , h as n ow ta k e n co n crete form . T h e te n d e n c y for som e tim e h a s b ee n to b rin g a b o u t a la rg e r a m a lg a m a tio n th a n th a t effected in 1921, w hen th e I n s titu tio n of M ining a n d M etallurgy a n d th e I n s titu tio n of M ining E n g in e ers jo in ed forces.
I t is d o u b tfu l, how ever, w h e th e r m a n y of th e in d iv id u a l m em b ers of th e v ario u s societies concerned a n tic ip a te d a n y th in g a p p ro a ch in g th e p re se n t a m b itio u s schem e. T h is involves th e lin k in g u p of no few er th a n tw elv e in s titu tio n s a n d societies, com prising th e I n s titu tio n of M ining an d M etallurgy, th e I n s titu tio n of M ining E ng in eers, th e I n s titu tio n of P e tro le u m T echnologists, th e Iro n a n d S teel I n s titu te , th e I n s titu t e of M etals, th e I n s titu t e of F u el, th e C hem ical Society, th e S ociety of Chem ical In d u s tr y , th e I n s titu t io n of C hem ical E ng in eers, th e I n s titu tio n of th e R u b b e r I n d u s try , th e F a r a d a y S ociety, a n d th e P h y sic a l Society.
T h e b u ild in g to house th e se is to be of a p a la tia l c h a ra c te r, as show n b y th e illu s tra tio n w e are ab le to give. T h e cost of th is
132 T H E M IN IN G M A G A Z IN E edifice, for w h ich a s u ita b le site is s ta te d to
h a v e b ee n fo u n d a t T o th ill S tre e t, W e st
m in s te r, to g e th e r w ith in c id e n ta ls, is p u t a t £350,000, for w h ich a n a p p e a l is m a d e to th e v a rio u s b o d ies con cern ed , a n d Sir A rn o ld T. W ilson, w ho is c h a irm a n of th e r e p re s e n ta tiv e s co m m itte e , h a s s ta te d t h a t
£100,000 h a s b ee n pro m ised . T h e v a rio u s bodies h av e , th ro u g h th e ir councils, ag reed in p rin cip le to th e schem e. T h e n ew s tr u c tu re is, how ever, n o t to b e confined to th e uses of te c h n ic a l a n d scientific in s titu tio n s , b u t in d u s tria l bodies are to becom e te n a n ts , a n d a lre a d y tw o — th e N a tio n a l F e d e r a tio n of
be desired. T h e re m o v a l to C ity R o a d met w ith a c e r ta in a m o u n t of d is a p p ro v a l;
we fea r th e p ro p o se d re m o v a l to W estm in ster w ill be ev en m o re unw elcom e. T h e present te n d e n c y seem s to b e in th e d irec tio n of com bines on a g ig a n tic scale ; w h e th e r this is alw a y s to th e a d v a n ta g e of th e various bodies co m p rised th e re in m a y b e open to d o u b t. A t a n y r a te , th e e n d to be desired so fa r as th e I n s titu t io n of M ining and M e tallu rg y is co n c ern ed is— as also sta te d in th e Ma g a z in e of M ay, 1921— the s tr e n g th e n in g of th e s ta tu s of th e mining engineer.
S K E T C H E L E V A T IO N O F P R O P O S E D F R O N T A G E .
Iro n a n d S teel M a n u fa c tu re rs a n d th e M ining A sso ciatio n of G re a t B r ita in — h a v e ex p ressed th e ir desire in th is d ire c tio n . T his, it is p o in te d o u t, w ill serv e to b rin g th e sales a n d m a n u fa c tu rin g side of in d u s try in to to u c h w ith th e scientific side, to th e ir m u tu a l a d v a n ta g e .
T u rn in g fro m th e g en e ral to th e p a rtic u la r, th e Ma g a z i n e, w h ilst fu lly s y m p a th e tic w ith th e aim s a n d o b je c ts of all th e bodies in c lu d ed in th e schem e, is m a in ly co n cern ed w ith th e I n s titu tio n of M ining a n d M etallu rg y . S ta r tin g in th e C ity, th is h a d th re e successive ad d resses, each a lm o st w ith in a s to n e ’s th ro w of th e o th e r, a n d it w as su rro u n d e d b y th e offices of m a n y of its m e m b ers, n a tu r a lly to th e ir g r e a t convenience.
I n 1921, as a lre a d y s ta te d , th e I n s titu tio n w as m o v e d n e a rly a m ile o u t of th e C ity a n d , w h ilst th is w as re g a rd e d as a go o d fin an c ial d ea l a n d g av e d o u b le th e floor space of th e F in s b u ry Circus b u ild in g , w h a t w ere fac etio u sly called th e a m en ities le ft m u c h to
T h e In d ia n B u d g e t
T h e re a re tw o m a tte r s of in te re s t for re a d e rs of th e Ma g a z in e a risin g o u t of the I n d ia n B u d g e t for th e com in g financial y e a r. T h e p ro p o sa l to in c re ase th e excise d u ty on k ero sen e a n d to re d u c e th e im port d u ty com es a s a so m e w h a t surprising se q u el to th e e v e n ts w h ich w ere discussed a t som e le n g th in th e se co lu m n s in October, 1928. T h u s th e m e a s u re of protection w h ich th e in d ig e n o u s oil in d u s tr y was en jo y in g , a n d for a n in c re ase of which it w as seek in g , as re c o rd e d a t t h a t time, is n ow in fa c t red u c ed . T h e in te n tio n , as disclosed in th e B u d g e t p re s e n te d to the L eg isla tiv e A sse m b ly la s t m o n th , is to raise th e excise d u ty on I n d ia n refined k erosene fro m one a n n a to one a n n a six pies a n d to low er th e d u ty on th e im ported p ro d u c t of w h a te v e r o rig in fro m tw o and a h a lf to tw o a n d a q u a r te r a n n a s. As w as d e m o n s tra te d in th e se co lu m n s a t the
tim e allu d ed to , th e G o v e rn m e n t is, a n d has b een for som e tim e, e v id e n tly of op in io n th a t th e In d ia n E m p ire p ro d u c e rs h a v e been selling a t e x o r b ita n t p rices a n d n ow shows itself to b e even less sy m p a th e tic to th e ir in te re s ts th a n it w as th e n . T he consum er in In d ia is th o u g h t, in fac t, to h av e suffered long enough.
O th er new ta x a tio n to b e im posed includes th e r é in tro d u c tio n of th e silver d u ty of four a n n a s p e r ounce, full re b a te being allow ed for th e re -e x p o rt of th e m etal. T his is less su rp risin g , co n sidering th e long co n tin u e d fall in th e p rice of th e m etal a n d h a v in g re g a rd to th e fa c t t h a t th ere is an obvious a d v a n ta g e in im p ro v in g th e in te rn a l p rice of a c o m m o d ity in w hich th e savings of th e g re a t m a ss of th e people are in v ested . I t sh o u ld b e rem e m b ere d th a t in In d ia th e av e ra g e c u ltiv a to r does n o t deposit his sav in g s in a b a n k ; h e e ith e r buries th e m se c re tly or, m o re generally, purchases jew ellery for his w om enfolk.
Much of th is jew ellery is m a d e of silver.
Sir George S ch u ste r, on th e o th e r h a n d , w hen ex p lain in g th is ta x , m a d e it q u ite clear t h a t th e G o v ern m e n t w ere w illing, so far as th e sale of su rp lu s silv er is con
cerned, to co -o p e ra te w ith o th e r im p o r ta n t in te rests in th e w o rld if th e se show ed a n y desire to co n sid er th e p o ssib ility of jo in t action for th e re g u la tio n of sales in accordance w ith w o rld d em an d .
W hile th e ta x a tio n chan g es h ere in d ic a te d will ad v ersely affect th e in d ig en o u s oil in d u stry , th e y sh o u ld p ro v e beneficial to the m ining in d u stry . I n th e case of th e B urm a C o rp o ratio n th e ir c o n tra c ts s tip u la te th a t in th e e v e n t of th e d u ty on im p o rte d silver bein g in c re ase d th e a m o u n t of th e increase is to b e a d d e d to th e p rice th e corporation is p a id for th e m etal.
A Q u e stio n o f E th ic s
T here h a s b een a good d ea l of p e r tu r b a tio n in som e q u a r te rs w ith re g a rd to th e assista n ce th e R u ssia n G o v ern m e n t is receiving from m in in g engineers to enable th e m to resu m e o p e ra tio n s on a t le a st one of th e confiscated p ro p e rtie s in t h a t c o u n try . No g roup h a s suffered m o re th a n th e R usso- A siatic C o rp o ratio n in th is d irec tio n , so th e p r o te s t of Mr. Leslie U rq u h a r t could h a rd ly h a v e occasioned surprise. T h e p a rtic u la r p ro p e rty to th e w o rk in g of w hich A m erican a n d C o n tin e n ta l engineers are now d irec tin g th e ir energies is th e R id d er.
W ith o u t th is a ssista n ce it is d o u b tfu l w h e th e r th is o r a n y of th e o th e r m ines of th e c o u n try co u ld be successfully re -s ta rte d . So fa r as th e R u sso -A siatic p ro p e rtie s are concerned, th e re h a v e b een n e g o tia tio n s for th e ir r e tu rn , b u t th e ag re e m e n ts rea ch ed h a v e n o t b een k e p t. P e rh a p s it is as well for th e c o rp o ra tio n t h a t th is h a s been th e case, in view of th e experience of th e L en a Goldfields.
A t th e p re s e n t tim e th e n u m b e r of A m erican m in in g engineers engaged in R u ssia cou ld p r o b a b ly b e c o u n te d on th e fingers of one h a n d , b u t t h a t th e re sh o u ld b e a n y is to b e re g re tte d — a n d th is re g re t is felt b y le ad in g m in in g m e n in th e U n ite d S ta te s as w ell as here. T h e p r o p e r ty on w hich th e y are engaged b elonged to an E n g lish co m p an y , form ed in ac co rd an ce w ith th e law s th e n in existence, a n d a large a m o u n t of m o n e y w as e x p e n d e d on its e q u ip m e n t a n d d ev e lo p m e n t. T h e re is o n ly one w ord w h ich covers th e forcible ac q u isitio n of such a p r o p e r ty w ith o u t com p en satio n . A lth o u g h to assist in th e re-opening of a m in e u n d e r such circ u m sta n ce s is n o t in th e sam e c a te g o ry as receiving stolen p ro p e rty , it is su re ly a b e ttin g . T h a t o th e r c o u n tries h a v e failed to fulfil th e ir o b ligations
— a view p u t fo rw ard in m itig a tio n of th e a c tio n of th e p re se n t regim e— is no ju stific a tio n , a n d in th is connexion th o u g h tfu l p eople m u s t o ften h a v e felt su rp rise d t h a t a w e a lth y c o u n try sh o u ld b e w illing to see c e rta in of its S ta te s p erio d ically scheduled as d e fa u lte rs b y th e C ouncil of F oreign B ondholders.
W h a te v e r th e o u tco m e of th e p re se n t c o n tro v e rs y m a y be, it is to be h o p ed th a t th o se in co n tro l in R u ssia m a y y e t realize th a t cou n tries, like in d iv id u als, c a n n o t ex p e ct to benefit b y confiscation a n d re p u d ia tio n . U n til th is sta g e is rea c h e d e n c o u rag em en t sh o u ld n o t b e given to th e e x p lo ita tio n of e x p ro p ria te d p ro p ertie s, n o r sh o u ld th e p ro d u c ts th e re fro m b e m a r k e t
able. F o r som e tim e p a s t oil from p ro p ertie s co nfiscated b y th e R u ssia n G o v ern m e n t h a s b een a v a ila b le a t a p rice w hich w ould n o t h a v e b ee n possible h a d c a p ita l e x p e n d itu re in c u rre d in b rin g in g th e m to th e p ro d u c in g sta g e h a d to be considered, a n d th e sa m e ap p lies to o th e r com m odities.
In p u rc h a sin g th e se p ro d u c ts we h a v e re a lly p ro v id e d th e finance w hich h a s en ab led th o se in c o n tro l to c a rry on th e ir op eratio n s.
H ow m u c h longer is th is s ta te of affairs to c o n tin u e ?
R E V IE W O F M IN IN G
In tr o d u c tio n .— B usiness in th is c o u n try rem a in s d u ll a n d th e im m e d ia te o u tlo o k does n o t a p p e a r to b e to o cheerful, a lth o u g h th e la s t few d a y s h a v e w itn essed a so m e w h at b e tte r to n e for som e of th e m e ta ls. W ith th e a n n o u n c e m e n t of th e G o v e rn m e n t’s B u d g e t p ro p o sals a r e v iv a l m a y b e w itn e ssed ; m e a n w hile th e low ering of th e B a n k r a te to 4%
offers im p ro v e d tr a d in g co n d itio n s.
T r a n sv a a l.— T h e o u tp u t of gold on th e R a n d d u rin g F e b r u a r y w as 783,086 oz.
a n d in o u tsid e d is tric ts 35,102 oz., m a k in g a to ta l of 818,188 oz., as c o m p a re d w ith 882,801 oz. in J a n u a r y . A t th e e n d of F e b r u a r y th e n u m b e r of n a tiv e s w o rk in g a t th e g o ld m in es w as 196,752, as c o m p a re d w ith 190,663 a t th e e n d of J a n u a r y .
I n th e J a n u a r y issue of th e Ma g a z in e
i t w as re c o rd e d t h a t Mr. J o h n M a rtin , p re s id e n t of th e T r a n s v a a l C h a m b e r of M ines, h a d e x p re ssed th e view th a t, a lth o u g h th e n a tiv e la b o u r su p p ly w as th e n a b n o rm a lly low, h e to o k a h o p efu l view of th e fu tu re . T h e em b arg o r e c e n tly p la c e d b y th e N o rth e r n R h o d e sia n G o v e rn m e n t on re c ru itin g in t h a t colony a n d th e su b se q u e n t n e g o tia tio n s for in c re a se d r e c ru itin g fac ilities in P o rtu g u e s e te r r ito r y m u s t h a v e fo rced Mr. M a rtin to ch an g e his o p in io n , for he now s ta te s t h a t h e fears th e g o ld -m in in g in d u s try w ill h a v e to face th e p e rm a n e n t p ro b lem of a sh o rta g e of n a tiv e la b o u r.
T h e a m a lg a m a tio n of th e V illage D eep a n d R o b in so n D eep h a s n o w b ee n a p p ro v e d a n d it is s ta te d t h a t, p ro v id e d th e co m p an ie s c a rry o u t th e u n d e rta k in g s giv en in re g a rd to e m p lo y m e n t a n d th e co m p e n sa tio n of em ployees, th e M in ister of M ines w ill h a v e no o b je c tio n to th e m erger.
T h e U n io n G o v e rn m e n t is in v itin g te n d e rs for leasin g 1,500 claim s in th e V o g elstru is- fo n tein are a, a d jo in in g th e C o n so lid ated M ain R eef p r o p e r ty on th e e a st a n d th e N ew S te y n E s ta te on th e w est. T h e a re a in q u estio n w as fo rm e rly w o rk e d b y th e B a n tje s N ew R eef C om p an y . I t is also s ta te d t h a t th e Crow n R eef a n d C onsolidated M ain R eef c o m p an ies a re a c q u irin g 900 claim s on th e farm D iepkloof, w h ich lies on th e d ip of th e ir ex istin g w orkings.
T h e re p o r t of th e T w ee fo n te in U n ite d C ollieries for th e y e a r e n d e d S e p te m b e r 30 la s t show s t h a t coal sales to ta lle d 828,720 to n s, a n in crease of 15,244 to n s on th e p re v io u s y ear. T h e w hole of th is to n n a g e w as
p ro d u ce d from th e T w e e fo n te in Colliery.
T h e e q u ip m e n t of th e N ew W a te rp a n Shaft is a lm o st co m p le te d a n d th e s h a ft is expected to b e in use a t a n e a rly d a te .
C a p e C o lo n y .— T h e C ape A sbestos C o m p a n y p ro p o ses to in c re ase th e capital of th e c o m p a n y fro m £200,000 to £300,000 b y th e c re a tio n of 50,000 c u m u la tiv e 5%
P a r tic ip a tin g P re fe re n c e sh a re s of £1 and 50.000 O rd in a ry sh a re s of th e sam e value, th u s ra isin g th e n u m b e r of ea ch class to 150.000 sh ares. I t is in te n d e d to issue 25.000 of b o th P re fe re n c e a n d O rdinary sh a re s, in o rd e r to p ro v id e fu n d s to meet th e e x p a n sio n of b u sin e ss a n d to reim burse th e c o m p a n y for su b sc rib in g c a p ita l required b y E g n e p for its a m o site a sb e sto s mines.
T h e sh a re s h a v e b ee n offered to shareholders in th e p r o p o rtio n of one n ew sh a re for every fo u r held, a t 12s. 6d. a n d 7s. 6d. prem ium fo r th e P re fe re n c e a n d O rd in a ry shares resp e ctiv ely .
I n a c irc u la r to s h a re h o ld e rs th e Griqua- la n d E x p lo r a tio n a n d F in a n c e Com pany s ta te s t h a t th e n ew m a c h in e ry is expected to b e sh ip p e d fro m E n g la n d in M arch and t h a t d e v e lo p m e n t of th e a sb e sto s deposits is p ro ce ed in g fa v o u ra b ly .
D ia m o n d s .— T h e o u tp u t of d ia m o n d s from th e U n io n of S o u th A fric a la s t y e a r was 3,661,212 c a r a ts , v a lu e d a t £10,590,000, a d ecrease fro m th e p re v io u s y e a r of 711,644 c a ra ts , o r r a th e r m o re th a n £6,000,000.
S ales of m in e d sto n e s in c re a se d b y 20s. 6d.
p e r c a r a t a n d th e d ec rease is e n tire ly in a llu v ia l sto n es, th e v a lu e of w h ic h dropped 34s. p e r c a ra t. M ined sto n e s w ere v alu ed at
£5,750,000, a n in c re ase of £150,000 on the p re v io u s y ea r.
T h e D ia m o n d C o rp o ra tio n , a com pany w ith a c a p ita l of £2,500,000, h a s b een regis
te re d in P re to ria , w ith th e h e a d office in K im b e rle y . A m o n g th o s e c o n n e c te d with th e r e g is tra tio n a re S ir E rn e s t O ppenheim er a n d Mr. S. B. Jo e l, a n d it is e x p e c te d th a t th e new c o m p a n y w ill p la y a n im p o rta n t p a r t in th e f u tu re of th e d ia m o n d in d u stry .
S o u th e r n R h o d e s ia .— T h e o u tp u t of gold d u rin g J a n u a r y w as 46,121 oz., as c o m p a re d w ith 46,829 oz. in D ec em b e r and 46,231 oz. in J a n u a r y of 1929. O th e r ou t
p u ts in J a n u a r y w e r e : S ilv er, 6,112 o z .;
copper, 100 t o n s ; coal, 111,978 to n s ; ch ro m e ore, 30,493 to n s ; a sb e sto s, 4,775 t o n s ; m ica, 21 to n s.
134
I n his re p o r t to th e B ritis h S o u th A frica C om pany Mr. E . H . C lifford co m m en ts on th e c o n tin u e d d ecline of th e gold in d u s try in S o u th e rn R h o d e sia a n d its effect on th e fu tu re re v e n u e of th e co m p an y . I t is felt th a t a lth o u g h tw o n ew p ro d u c e rs— th e W a n d erer a n d th e M ay fair— cam e in to o p era tio n d u rin g th e y e a r th e y w ill n o t be able to a r r e s t th e c o n tin u o u s decline.
W ork a t th e S h a m v a m in e is to cease n o t la te r th a n M arch 31. O w ing to b a d w ea th er a n d o th e r co n d itio n s, c e rta in sections of th e m in e h a v e becom e d a n g e ro u s, a n d th e expense of k ee p in g th e m o pen is n o t w a rra n te d b y th e o re -re serv es a v a ila b le .
The d ire c to rs of R e ze n d e m ines p ropose to re p a y 2s. 6d. p e r ¿1 sh a re , w h ich will reduce th e issu ed c a p ita l to ¿131,250 in shares of 17s. 6d. each.
N orth ern R h o d e sia .— Som e useful sta tistic s for th e co p p e r m in in g in d u s try in N o rth e rn R h o d e sia are c o n ta in e d in Mr. Clifford’s re p o rt to th e C h a rte re d C om pany. H e s ta te s t h a t p ro v e d ore a m o u n ts to 230,000,000 to n s, c o n ta in in g an average of 3-9% copper. In c lu d e d in th is to ta l are th e 60,000,000 to n s of oxidized ore w hich h a v e b een p ro v e d in th e n e ig h b o u r
hood of th e N ’C h a n g a m in e a n d for w hich a su itab le tr e a tm e n t process h a s y e t to be found. T h e re m a in in g ore, how ever, Mr.
Clifford sta te s, is a stra ig h tfo rw a rd su lp h id e ore, av e rag in g 4 % copper, a b o u t w hich th e re is no u n c e r ta in ty , e ith e r in resp e c t of q u a n tity , v alu e, o r tr e a tm e n t. F u r th e r m ore, th e in d ic a tio n s leav e no d o u b t as to th e existence of a f u rth e r 100,000,000 to n s w hich will sh o rtly b e p ro v e d b y drilling. I t is fu rth e r p o in te d o u t b y Mr. Clifford th a t no difficulties a re a n tic ip a te d as to an a d e q u a te su p p ly of w h ite la b o u r, b u t he a d m its t h a t th e p ro b lem of n a tiv e la b o u r m a y p re se n t som e tro u b le .
S hareh o ld ers of th e R h o d e sia n Congo B order Concession h a v e n ow been in fo rm ed of th e com plete re su lts from bore-hole N .E . 8, s itu a te d on th e w e ste rn ex ten sio n of th e N ’C hanga p ro p e rty . T h e in te rp re ta tio n of th is hole show s t h a t from 1,270 ft. to 1,369 ft.
it was in ore a v e rag in g 9-72% copper, of w hich 94-3% is p re se n t in th e form of sulphide.
G old C oast.— I t is p ro p o sed to red u ce th e c a p ita l of T a q u a h a n d A bosso M ines from ¿250,000 to ¿200,000 b y red u c in g th e 5s. sh a re s to 4s. W hen th e re d u c tio n h as been a p p ro v e d it is p ro p o sed to cre ate 250,000 new sh ares of 4s. each, w hich will
re sto re th e c a p ita l to ¿250,000. T h e re d u c tio n , it is h o p ed , w ill en ab le th e c o m p a n y to re a c h th e d iv id e n d -p a y in g sta g e again.
A u str a lia . — A n asb esto s p ro p e rty , s itu a te d th re e m iles s o u th of th e S oanesville A sb esto s m ine, P ilb a r ra d is tric t, W e ste rn A u stra lia , a n d kn o w n as th e " S o u th S oan esv ille,” is to be a c q u ire d b y N igel (T ran sv aal) G oldfields, L td . T h e a re a is a b o u t 540 acres in e x te n t, a n d th e m in e ra l is a ch ry so tile asb esto s of good q u a lity fibre.
Mr. H . R . S leem an h a s re p o rte d on th e p r o p e r ty a n d som e p ro m isin g d ev e lo p m e n t w o rk h a s b een done. I t is p ro p o sed to in crease th e c a p ita l of th e co m p a n y to
¿125,000.
T h e E le c tro ly tic Z inc C o m p an y of A u stra la sia sto p p e d fo rw ard in g ore to Z eehan a t th e en d of J a n u a r y on a c c o u n t of th e re m o v a l of p la n t to w orks a t R osebery.
T h e m ill a t R o seb ery is ex p e c te d to s ta r t w ork in Ju n e .
T h e serious d am ag e d one b y th e floods in A pril la s t on th e B riseis m ine am o u n te d to o v er ¿62,000 a n d th e cost of re-o p en in g a n d re-eq u ip p in g th e w orkings is e s tim a te d a t ¿65,000. T h e T a sm a n ia n G o v ern m e n t h a s a g re e d to a lo a n n o t exceed
in g ¿25,000, a n d i t is n ow p ro p o sed to re c o n s tru c t th e co m p an y , w ith th e sam e c a p ita l as a t p re se n t, th e new sh a re s c a rry in g a lia b ility of 3s. a share.
M a la y a .—D u rin g th e y e a r en d ed O ctober 31 la s t, P e ta lin g T in, L td ., tre a te d 6,183,682 cu. y d . of g ro u n d a n d rec o v ered 2,469 to n s of tin co n c e n tra te s. T h e to ta l p ro fit from m in in g o p era tio n s w as ¿202,610, a n increase of ¿98,013 over t h a t of th e p rev io u s y e a r, a n d ¿130,200 w as d is trib u te d as divid en d s, e q u a l to 60% . T h e a re a w o rk ed o u t in th e p erio d u n d e r review w as a p p ro x im a te ly 77 acres. A t th e g en e ral m e etin g la s t m o n th it w as an n o u n c ed t h a t in stru c tio n s h a d b een giv en to close dow n N o. 1 d red g e a n d to tu r n N o. 2 d redge in to g ro u n d of a low er g rad e. T h e fo rm er is to b e rep la c e d b y a 15 cu. ft. d redge cap ab le of tr e a tin g 220,000 cu. y d . p e r m o n th , e s tim a te d to cost ¿100,000.
I t w ill b e recalled t h a t th e d ire c to rs of th e K a y Y ew (K in ta V alley) T in M ines n o t b ein g satisfied w ith Mr. A tte n b o ro u g h ’s re p o rt on th e ir p ro p e rty a p p o in te d Mr.
F re d e ric k W ic k e tt as m a n a g e r a n d elected Mr. N an c e W illiam s to th e b o ard . Mr.
W illiam s is a t p re se n t in M alay a a n d it is s ta te d th a t, w h ilst th e m e th o d he h as a d o p te d to o pen u p th e p r o p e r ty will h a v e
136 T H E M IN IN G M A G A Z IN E th e effect of te m p o ra rily re d u c in g th e o u t
p u t, p r o d u c tio n b y th e e n d of A p ril will h a v e in c re a se d to 500 p icu ls p e r m o n th , p u ttin g th e m in e on a p ro fit e a rn in g basis.
T h e P e n a w a t (M alaya) T in D re d g in g C o m p an y a n n o u n c es t h a t n e g o tia tio n s h av e b een c o m p le te d fo r th e p u rc h a se of 833 acres of tin -b e a rin g la n d s itu a te d a t M alim N a w a r M ukim , in th e K a m p a r D is tric t of K in ta P e ra k , to g e th e r w ith one b u c k e t dredge. Of th e n e w ly -a c q u ire d a re a 327 acres, e s tim a te d to c o n ta in 23,879,853 cu. yd . of a n av e ra g e v a lu e of 0-47 k a t ty , h a v e been p ro v ed . T h e p u rc h a se c o n sid e ra tio n is 500,000 fu lly p a id sh a re s. Mr. E . P.
H a rg re a v e s h a s r e p o r te d on th e p ro p e rty , w hich h a s b ee n ch e ck -b o red b y th e c o m p an y , a n d a fa v o u ra b le re p o rt of th e d re d g e w as g iv en b y Mr. C. H . S h a rp , of th e M a lay a C o n so lid ated T in D re d g in g C om p an y . I t is e s tim a te d t h a t th e d red g e w ill com m ence digging a b o u t N o v e m b e r n e x t.
In d ia .— I t is now n e a rly a y e a r since th e re w as tro u b le fro m ro c k -b u rs ts in th e I n d ia n m ines. T o w a rd s th e e n d of F e b ru a ry , h o w ev er, ro c k -b u rs ts w ere r e p o r te d from th e O o reg u m a n d C h am p io n R eef. A t th e O oregum a h e a v y b u r s t o cc u rre d in B u lle n ’s se ctio n , w h ich re s u lte d in in ju rie s to 13 w o rk m en , w h ilst th e C h a m p io n R eef a n n o u n c es t h a t tw o ro c k -b u rsts o cc u rre d in G a rla n d ’s se c o n d a ry s h a ft from th e 3 9 th to 5 5 th levels. I t is n o t e x p e c te d t h a t o u tp u t will b e serio u sly affected in e ith e r case.
U n ite d S ta te s.— T h e e s tim a te d to ta l v a lu e of m in e ra l p ro d u c ts in th e U n ite d S ta te s in 1929 w as a p p ro x im a te ly
$5,900,000,000. T h is is a n in c re ase of n e a rly 10% o v er th e v a lu e fo r 1928 a n d is d u e chiefly to th e in c re ase in q u a n t ity of co p p e r a n d iro n p ro d u c e d . L ea d , zinc, a n d m in e ra l fuels in c re ase d , b u t gold a n d silv er decreased.
M e x ic o .— D u rin g th e la s t q u a r te r of 1929 th e F re sn illo m ill c ru sh e d a n d tr e a te d 216,329 s h o rt to n s of o x id e ore a n d 62,458 s h o rt to n s of su lp h id e ore, a t o ta l of 278,787 to n s, a n d th e v a lu e of b u llio n a n d c o n c e n tra te s p ro d u c e d w as $1,255,713. A t th e T e z iu tla n th e m ill c ru sh e d a n d tr e a te d 15,392 s h o rt to n s of su lp h id e ore, p ro d u c in g c o n c e n tra te s w o rth $191,649.
T h e re p o r t of th e S a n ta G e rtru d is C o m p an y for th e q u a r te r e n d e d D ec em b e r 31 la s t s ta te s t h a t on th e D os C arlos G ro u p 10,826 ft. of d e v e lo p m e n t w o rk w as done, of w h ich 5,792 ft. w as in ore. I n a c co rd an c e w ith th e a rra n g e m e n t w ith th e R e a l del M onte, d riv in g w as c o n tin u e d alo n g th e
n o r th b o u n d a ry of th e O hio claim for a d ista n c e of 524 ft., all in c o u n try rock.
D rillin g in p ro g re ss alo n g th e b o u n d ary b e tw e e n th e R ia lito a n d O hio claim s has c u t 28 ft. of h ig h -g ra d e ore. T h is is th o u g h t to b e a n o r th -s o u th v e in a n d assay s of the 6 ft. of core re c o v e re d w e n t 60 oz. silver to th e to n .
V e n e z u e la .— P ro m isin g d e v e lo p m e n t of th e p r o p e r ty a c q u ire d fro m th e N orth V en e zu e lan ' P e tro le u m C o m p an y is an n o u n c e d b y T o c u y o O ilfields of V enezuela, L td . I n a d d itio n to th e three p ro d u c in g w ells d rille d b y th e fo rm er com
p a n y , eleven fu rth e r w ells h a v e b ee n brought in a n d fo u r w ells a re in course of drilling.
A p ip e lin e 33 k ilo m e tre s in le n g th , connecting th e fields w ith th e sea, is e x p e c te d to be c o m p le te d in th e n e a r fu tu re , a n d m eanwhile p ro d u c tio n is b e in g re s tric te d .
R u ssia .— D u rin g th e p a s t m o n th there h a s b ee n a p le th o r a of re p o r ts of a conflicting c h a ra c te r c o n c ern in g th e L e n a Goldfields a n d th e S o v iet G o v e rn m e n t, th e la te s t being to th e effect t h a t th e v a rio u s m a tte rs in d isp u te a re to b e s u b m itte d to a rb itra tio n .
A s b e s to s .— T u rn e r a n d N ew all, L td ., has a c q u ire d th e w hole of th e sh a re c a p ita l of th e Q uasi-A rc C o m p a n y a n d its ow n capital is, in consequence, to b e in c re ase d to
¿7,250,000 b y th e c re a tio n of 400,000
¿1 sh ares.
C h e m ic a l a n d M e ta llu r g ic a l C orpora
tio n .— F o llow ing th e d is p u te b etw een the c o m p a n y a n d its g e n e ra l m a n a g e rs , th e re has b ee n a good d ea l of re stiv e n e ss am ong the sh a re h o ld ers, w ho h a v e h e ld a m e e tin g and a p p o in te d a c o m m itte e . T h e a n n u a l general m e e tin g is to b e h e ld th is m o n th , w hen the p o sitio n of th e c o m p a n y is to b e fu lly dealt w ith.
T in .— T h e re g u la tio n of th e production of tin c o n c e n tra te s is n o w a s su m in g definite form . T h e p ro d u c e rs of th e D u tc h E ast In d ie s w ill lim it th e o u tp u t of B a n k a to 22.000 to n s a n d t h a t of B illito n to the a v e rag e p r o d u c tio n of th e p a s t th re e years.
C om panies w h ich a re m e m b e rs of th e Tin P ro d u c e rs ’ A sso c iatio n a n d w h ich a re actually c u rta ilin g o u tp u t n u m b e r 104, a n d their n o rm a l a n n u a l p r o d u c tio n is given as e q u iv a le n t to o v er 47,000 to n s of m etallic tin . O th e r p ro d u c e rs o u tsid e th e association, w ith a n o rm a l a n n u a l o u tp u t of o v er 68,000 to n s m e ta llic tin , h a v e also u n d e r ta k e n to r e s tr ic t p ro d u c tio n . T h e a g g re g a te annual c u rta ilm e n t is n ow c o m p u te d a t over
24.000 tons.
By R . E . B Y L E R
T h e a u th o r , w h o is m e ta llu rg is t to th e F re s n illo C o m p a n y , d e s c r ib e s th e p r a c tic e o n th is s ilv e r - le a d - z in c p r o p e r ty , s itu a te d in th e S ta t e o f Z a c a te c a s , M e x ic o .
v h ic h
T h e c y a n id a tio n of oxidized silver ore a n d the c o n c e n tra tio n of lead -silv er-zin c sulp h id e ore b y d ifferen tial flo ta tio n com prise th e m etallu rg ical o p e ra tio n s a t F resnillo. B ene- ficiation of th e ox id e ore, w h ich is m in e d from a la rg e surficial ore d ep o sit, w as beg u n on a 2,200 to n - p e r - d a y 1 b asis in 1921 b y th e M exican C o rp o ratio n , S.A. T h is c o m p an y developed th e p r o p e r ty a n d o p e ra te d it under a le a se -c o n tra c t ag re e m e n t w ith th e owners, th e fo rm e r F re sn illo C o m p an y of New Y ork, u n til M ay, 1929, w h en th e in terests of b o th com panies in th e p ro p e rty were m erged to form th e p re se n t F resnillo C om pany. M ining a n d m illing o p e ra tio n s were confined to th e oxidized silver ore u n til 1925, w hen e x p lo ita tio n of th e su lp h id e ore- body u n d erly in g th e surficial o x id e ore w as begun a n d a flo ta tio n p la n t w as b u ilt to tr e a t the com plex su lp h id e ore.
P ro fitab le tr e a tm e n t of th e oxide ore p redicates econom y of p ra c tic e a n d close a tte n tio n to sm all econom ic gain s or losses, as th e ore is low g ra d e a n d th e silver is associated w ith m a n g an e se o x id es in a form which reduces its a m e n a b ility to cy a n id a tio n . The average ore m illed d u rin g th e six -y ear period 1921 to 1927 c o n ta in e d 5 J oz. of silver a n d 16 ce n ts in gold p e r to n . T he ca p ac ity of th e m ill w as in c re a se d to 3,750 tons per d a y in 1924, a n d th is to n n a g e w as m a in ta in e d u n til 1927. Since 1927 th e g ra d e of th e ore h a s a v e ra g e d 6 | oz. of silver a t a m illing r a te of 2,500 to n s p er day . T h e ore from som e sections of th e m ine is sufficiently refra cto ry , in consequence of th e m an g an ese- silver association, to re q u ire a special p re lim in ary tr e a tm e n t b efore a n econom ic e x tra c tion of th e silver c a n b e o b ta in e d b y c y a n id a tion, a n d th is tr e a tm e n t is given in a 400-ton p la n t b y th e M cCluskey process, w hich w as developed a t F resnillo. T h e c u rre n t sulp h id e ore co n tain s 9 '5 % le ad , 10% zinc, 0-65%
copper, a n d 11-5 oz. of silver p e r to n . T h e base m e ta l c o n te n t of th e ore h a s a p p ro x i
m a te ly d o u b le d since 1925. T h e to n n a g e of ore tr e a te d in th e flo ta tio n p la n t h a s been increased from 165 to 690 to n s p e r d a y , in co-ord in atio n w ith th e d ev e lo p m e n t of th e
1 Tonnage data refer to the short ton of 2,000 lb., and costs are expressed in U nited States currency.
su lp h id e o re-body. O p e ra tin g costs h av e b een red u c ed , a n d tr e a tm e n t of b o th th e oxide a n d su lp h id e ores h a s b ee n c o n tin u o u sly im p ro v e d u n d e r th e v igorously p ro g ressiv e p olicy of th e m a n a g e m e n t. T h e p re s e n t cost of th e oxide ore tr e a tm e n t b y cy a n id in g is fl'O O p er to n , w hich is slig h tly low er th a n th e co st o b ta in in g a t th e fo rm er h ig h e r m illing r a te of 3,650 to n s p e r d ay . T h e cost of c o n c e n tra tin g th e su lp h id e ore h a s b e e n re d u c e d from $2'55 to $T 3 6 p er to n , a n d th e flo ta tio n p ra c tic e h a s b ee n g re a tly sim plified.
T h e tr e a tm e n t of th e oxide a n d su lp h id e ores is describ ed in th e follow ing a c c o u n t of F resnillo m illing p rac tice .
Cr u s h i n g Pr a c t i c e.—T h e cru sh in g a n d g rin d in g p la n ts, orig in ally designed for th e oxide ore, are now u se d for b o th oxide a n d sulp h id e ores. T h e tw o classes of ore a re cru sh e d s e p a ra te ly a n d d eliv ered to s e p a ra te c o m p a rtm e n ts of a n 8,800 to n cru sh e d -o re sto rag e b in a t th e h e a d of th e g rin d in g p la n t.
O re is d eliv ered to th e c ru sh in g p la n t b y electric h au la g e in tra in s of te n 12-ton c a rs each, a n d is d u m p e d d ire c tly in to th e h o p p e r of th e p rim a ry b re a k e r. C rushing is d one in th re e sta g e s ; th e p r im a ry b re a k e r, a 30 in.
MrC.nlly g y ra to ry , red u c es run -o f-m in e ore to 3 | in. or u n d er, th is p ro d u c t bein g re d u c e d to 1 | in. b y tw o 48 in. S ym ons h o riz o n ta l disc crushers, a n d th e n to th e final p ro d u c t c o n ta in in g 22% - f f in. a n d 22% + £ in., b y tw o 48 in. S ym ons v e rtic a l disc crushers.
A s ta tio n a ry grizzly rem o v es th e — 1 | in.
m a te ria l from th e feed to th e h o riz o n ta l disc cru sh ers, a n d M itchell v ib r a tin g screens h a v in g J in. a p e rtu re s rem o v e th e u n d e r
size fro m th e feed to th e v e rtic a l disc crushers. W h e n o p e ra tin g on oxide ore alone th e c ru sh e r p la n t deliv ered a § in. p ro d u c t, b u t ow ing to th e te n d e n c y of th e m o ist su lp h id e ore fines to p ac k , i t h a s b een n ec essary to increase th e o pening of th e disc cru sh e rs a n d deliver a co a rser p ro d u c t to th e g rin d in g p la n t. T h e a v e rag e coarse c ru sh in g cost, in c lu d in g conveying, is 5 J ce n ts p e r to n of ore, a n d th e pow er c o n su m p tio n 0-88 kw .-h r. p e r to n .
Ox i d e Or e Tr e a t m e n t.— T h e g rin d in g p la n t is d iv id e d in to fo u r in d e p e n d e n t u n its , one of w hich is now u se d for th e su lp h id e 137
138 T H E M IN IN G M A G A Z IN E ore a n d th re e for th e oxide. W h e n re fra c to ry
m a n g a n e se -silv e r ore is b ein g ru n , h a lf of one o x id e ore g rin d in g u n it is d iv e rte d to th is ore. P rim a r y g rin d in g is d o n e in th e o x id e ore u n its b y 6 b y 12 ft. M arcy rod-m ills o p e ra tin g in o pen circ u it, a n d se c o n d a ry g rin d in g b y 6 b y 14 ft. T ra y lo r ball-m ills in closed c irc u it w ith 12 ft. D o rr bow l classifiers as show n in th e o x id e ore flow -sheet (Fig. 1).
T h e p ow er co n su m p tio n , in c lu d in g classify
ing, is 12-7 k w .-h r. p er to n of ore, a n d th e co st of g rin d in g is 30 c e n ts p e r to n . T h e co n su m p tio n of liners a n d g rin d in g m e d ia is given in T ab le I. A re d u c tio n in th e co n su m p tio n of m ill lin e rs h a s b ee n effected b y th e use of m a n g a n e se ste el in s te a d of w h ite - iro n liners, th e re d u c tio n a m o u n tin g to 50%
for M arcy ro d -m ill liners.
T a b l e I.
f . i N E R , Ro d, a n d Ba l l Co n s u m p t i o n Ox i d e a n d Su l p h i d e Or e Mi l l i n g Un i t s.
Lb. per short ton.
Oxide Sulphide Ore. Ore.
Mn steel liners— Prim ary rod-mills 0-206 Prim ary ball-m ills — 0 ■ 352 Secondary ball-m ills 0 • 204 0 -124 3 in. high-carbon steel rods . 1-416
3 in. forged steel balls (secondary
m i l l s ) . . . . 0 -9 4 8 1-020
4 and 5 in. forged steel balls
(primary mills) . . . — 3 -188 E x tr a c tio n of th e silver fro m th e oxide ore is im p ro v e d in p ro p o rtio n to th e degree of co m m in u tio n , b u t th e e x te n t to w h ich fine g rin d in g can b e econom ically c a rrie d is lim ite d b y th e low g ra d e of th e ore. I n o rd e r to o b ta in th e h ig h e st econom ic o u tc o m e from th e tf e a tm e n t, th e re fo re , th e ore w as fo rm e rly se g re g ate d ac co rd in g to g ra d e a n d d iffe ren tia l g rin d in g p ra c tise d , one m ill u n it b ein g u se d for ea ch g ra d e of ore. A fte r g rin d in g , th e p u lp from all u n its w as co m b in e d for c y a n id a tio n . A s u m m a ry of d a ta re p re se n tin g th is p ra c tic e a n d sh o w in g th e re la tio n b e tw e e n e x tra c tio n a n d deg ree of co m m in u tio n of th e se g re g ate d g rad e s of ore, follows :—
Ground Extrac- Short tons A ssa y % - 200 Hon.
Class. per day. oz. Ag. mesh. %
No. 1 865 6 • 5 67 75
,, 2 885 5 -5 54 72
3 950 5-0 53 71
,, 4 1050 4 -5 51 68
T h e low er g ra d e ores cam e fro m th e u p p e r levels of th e oxide o re-b o d y a n d th e h ig h e r g ra d e , m a k in g u p class N o. 1, fro m th e low er levels from w h ich th e m a jo r p a r t of th e
c u r re n t ore is b ein g m ined. W h e n m in in g of th e h ig h e r g ra d e o x id e ore w as b eg u n in 1927, th e p ra c tic e of se g re g a tin g th e ore for g rin d in g w as d isc o n tin u e d , a n d all oxide ore m ill u n its now g rin d to th e sam e degree of co m m in u tio n , 5 % + 65 m e sh a n d 60%
th ro u g h 200 m esh.
T h e oxide ore is c y a n id e d b y s a n d leaching a n d slim e a g ita tio n , 3 0% of th e tonnage b ein g tr e a te d in th e le ac h in g p la n t. T he ore w as fo rm e rly tr e a te d b y a g ita tio n of the w hole p u lp , b u t th is p ra c tic e w as ch an g ed to sa n d -slim e tr e a tm e n t in 1924, to low er the cost of c y a n id in g a n d to o b ta in a higher re c o v e ry of silv er fro m th e c o a rser com p o n e n ts of th e p u lp . W h ile sa n d leaching e n ta ils a n e x p e n d itu re of 2 c e n ts p er to n of ore, th e cost of a g ita tio n w as red u c ed by 7 c e n ts p e r to n b y th e re d u c tio n in tonnage of p u lp a g ita te d , so t h a t a n e t saving of 5 c e n ts p er to n w as m a d e in th e cost of tr e a tm e n t. T h e t o t a l re c o v e ry of silver is in c re ase d b y a n a v e ra g e of 0-15 oz. (5 gm .) per to n of ore b y th e s e p a ra te tr e a tm e n t of the sa n d a n d slim e. T h e fa c to rs c o n trib u tin g to th e in crease in e x tra c tio n a re : T h e use of stro n g e r so lu tio n s a n d a long c o n ta c t period in th e tr e a tm e n t of th e coarse sizes of the p u lp b y leach in g , a n d th e longer slime a g ita tio n a n d filte r-ca k e w ash in g periods w hich re s u lt from th e re d u c tio n in to n n a g e of p u lp tr e a te d in th e a g ita to rs . A n ex tra ctio n of 4 5 % of th e silv er is o b ta in e d from the s a n d p ro d u c t a n d 5 5 % fro m th e slim e. The m o re a m e n a b le silv er is disso lv ed w hile the ore is b ein g g ro u n d , a n d a n e x tra c tio n of 4 4 % is m a d e in th e m ills, th e t o ta l com bined e x tra c tio n b ein g 7 5 % . T h e ore contains 0-3 to 0-4% m a n g a n e se , w h ic h adversely affects its a m e n a b ility , so t h a t th e recovery o b ta in e d re p re s e n ts p ra c tic a lly com plete e x tra c tio n of th e solu b le silver, th e to ta l e x tra c tio n of g o ld b e in g 7 5 % .
T h e sa n d -slim e se p a ra tio n is m a d e b y two 15 ft. D o rr bow l-classifiers o p e ra tio n in p a ra lle l. C h a ra c te ristic screen an aly ses of th e tw o p ro d u c ts u n d e r c u rr e n t grinding p ra c tic e a re as follow s :—
Ty l e r St a n d a r d Sc a l e.
% + % + % + % + % -
48 65 100 200 200
Product. mesh. mesh. mesh. mesh. mesh.
Sand . 2 36 30 28 4
Slime .
.
- 0-5_
24-5 75T h e sa n d is le ac h ed in five ste e l ta n k s 60 ft. in d ia m e te r b y 16 ft. deep, e a c h having a c a p a c ity of 1,815 d ry to n s. A lth o u g h the s a n d ch arg es are u n u su a lly deep, a leaching
