Arizona weekly citizen., 1886-12-25
GOLD IN BLACK SAND.
A bHef Treatise on the Method of Deter
 mining its Value.

way.
 fiTst-Ihe wet process or analysis, as
 furnished by Bruno Kerl, Is one which
 giVes absolute Gccaracy, but requires
 considerable skill and experience. The
 concentrates are dissolved in aqua recin
 lone part ot nitric and two psris of by
 droohlOric gcids;) when completely dis. solved solution of manyangte of potas-
 slum IS slowly added, which precI2ltstes
 the Iron, etc, as oxides, This precipI- tate IS filtered of and a current of sul-
 phuretted hydrogen gas is pGssedtbrough
 thIs neutralized solution until yellcwish
 crystals ofsulphur appear IL the same.
 The resulting precipitaie is Uf a dark
 brown color and contains gold, silver,
 platinum, copper, bismuth, tin, cad
 mum, etc, (ot course provided that these
 metals existed in the concentrated The
 precipitBte IS now freed from the soiu-
 ton by filtration or decantstioC, and
 then alternately treated with nitrlc and
 hydrochloTio Ocids. In this manner sIi-
 yer, copper, tin, bismuth and cadmium
 are entirely dissolved L.d thus taken out
 tshid pTecipitRte and Crly gold aud pla-
 tinum remains. Diluted aqua regia will
 Eow dissolve the gold, iud none CT but
 very little platinum. This solution Is then evaporsted to nearly dr,ncss to re
 move acids, and then again dissolved
 m pure water; the gold may DOW readily
 De preoipiiated by a sriutCn of ferrous
 sulphate. The cnsnias prycIpitate IS
 dried and weighed, or Hlay be first
 smelted into battCn o' pare and solid gold.
 Another method. which gives very
 good results III god Ut Cf those COZ
 centr8tes, k prscticeG b. the jewellers to
 obtain the gold from the things. etc
 Such filiegs contain. besides gold, large quantities If steel, iron and some silver,
 copper, etc.
 By this method. as auOve, R certhin
 quantity of concentrates Ia weighed cut
 and then dissolved in aqua TegiB. When
 di solved little sulphuric scii k added e. the solution and some iron nails or
 other suitable pieces oi metallic irou are 1 introduced Intolt The ferrous sulpha:e
 is thus produced ID sgId solution, ard iron, chrome, etc. is suspended in the
 acidulsted solution, and only gold and l some little iron gre prccipitRtrd hficT
 some ume, and is generally finished ID ! from ten to fifteen hours. The preeIpi- [ tate Is tine same Bs above and IS, like it. 1 drIed and smelied into button and 1 weighed.
 To dissolve the gold 10 aqua reSia aud ! then precipitsIe It out of such solution directly by ferrous sulph6te, as prac- ticed for pure gold, or metallic alloys of gold with silver, copper. etc, | ses not and cannot give any results for such mixtures of metals and metBllolds as gre found in the above concentrates, or the so-called black sand.
 Second-The dry way or fire process. ! The best, quickest snd most practical 1 process (thus tsr) of obtaining good re suits m gold from the concentrates In l question IS the hydTC-oIygen blowpipe. | invented ID lI97 by Prof. Hare, If Phil | sdelphia, Penn. In s furnace construct ed by M. St Clair Deville, of Paris, | France, charge from a very little up | Co lOO pounds, properly huXed snd | mixed. ls completely reduced in from | 2O to 6O minutes. This process has not | only the advantage of giving the great est pyrometric effect, but also by il oxygen gas may at any moment be put on ID excess and thus the operation De changed from s reducing to an OxilIz- lng sDeltng, and vice versa, When | such concentrates contain any bismuth. tin or other desirable metals thas gre likely to be oxidizsd, they arc extracted by IlXlvlsnOn before smelling, If pOssi- ble. The regulus Is then refined ID tue usual way ln case platinum, silver, etc, were present ID the origiaal charge. mon!y pr8ctIced, gIves very unsatisfsc- tOEy results, because these conceutrates contain 4J per cent of metRlic iron, and usually q still larger amount; and these oxides of iron, with chrome oxides, etc. enclose to a great extent the fine parti- cles of Rold-both of some native gold and sulpEide of gold This fact may readily be seen by placing some of such under a powerful micro scope. which wIil thus show particles Of gold prOtruding out of the sides of some Of the grains of concentrates. Again. by dlssolving some of the larger pieces 1f concentrates in nitric acid (some ( pieces may thus be dissolved) a residu- ( lm of very small particles of gold Sill I result ln most cases. Moreover. in { many placer mines large pieces of iron Ere found which have native gold, yisi- Die Co the naked eye, on them or pro . irudIng out of them It k an absolute ( Tact that ID common 6ssay furnace c hardly ever sufficient heat Is produced 1 ! To smelt such iron ore, or fuse 10 such [ an extent that the mass becomes sniff 'ieotly hquid 10 permit the gold to set a ile out of the slBg to the bottom or to [ 'ome in contact with or be absorbed [ Jy the test lead. Moreover, the lead [ employed ID any assay of such concen. Il rates fuses and settles to the bottom of q he crucible long before the iron in the $ ame has even become thin paste or is used, while the smaller particles of lead I; Ire held suspended ID the hall molten nRss. According to good authority if is b ll large blast furnace can do 10 re- uce such ores even in IsmRll quantities & dded to other ores that fuse easier. s' In order tO obtain better results by D he ordinary assay 1t is Vt Il to roast sucb G leterIRl very carefully and iu a good e6t. The particles of iron, while thus o RAlnR up more oxygen, break into al mailer pieces and some of the gold k tl Iced from its enclosure; pulverizing to Il extremely fine powder and then fiux- lg for and smelling Bt s tolerable high n, eETee of heat. In smeltiDg oxldizIpC n. uXes should be added from tune Co time ntil sulphur fumes cease to escape. h, be smelling mRss should be stirred up J, intervals and then finally charge of tnsrge IS added. When the mass fuses 1ietly again, or is well fused, it is sS.' cured ell and the regulus treated in the =, sual way. co Another way. which gives approximate SSii ,sults, IS To treat the concentrates be a, re smelling alternately with nitric. A 'drochloric and sulphuric acids, taking . Ire that no aqua regis is formed, which ot ould dissolve the gold. Much material D iat lnterferes with the bringing out Of on 'id Is thus removed; it k then oi 'aln dried, pulverized and smeltei as na )Ove. co ID the Ursl mountains. in Russia, and ft her places in the same country. the o: neentratlons are obtaIned by the or 'eeping process since 1894, and has ii en snccess both in financial and fr' chnlcBl way. of
 th, la Iuck of a portu,.uo.,,, s-. 1,I l lI-