RI 2346 Acetylene As A Precipitant For Cyanide Solutions

In connection with some investigations being made at '!'he Ra.re uid Precious 􀄡1ets.ls Station of the U, S. Bu.rea.u of Mines, at Reno, Nev., on the precipitation of gol'i and silver from cyanide solutions, it wa.s sug­ gested tnat the use of acetylene for this purpose be investigated, A pa.tent was iss·.ied to Fre<!.erick W. Martin and Frederick Stl1.bbs in 1900 covering the precipitation of precious metals from cyanide solu­tions by acetylene, The acetylene used in the tests described below wa3 made f'rom a. corr.:nercial cal ci \'!Z:l carbid.e, A r..umber of exper:me11. +,s rezul ted in more or lP.ss ccmplete pree;p1tatien of silver, -but 1n no case was a11Y gold precipitated. As silver acetylide, obtained by precipitatir.g the silver from an ar:::ncni'i\.Ca.l so1ut1on of silver n,. tra.te by acetylene, is yellowish white, e􀋡sn:, solu'.)le in cyanide and hlghly explosive, and the pr9cip1tate ob­tain£􀌖 frcvm the cy'31lide sclutions was black, not t􀌴lubla L., cyanide and not explooive, it 'Na.s de􀍓id-,d. to ir.·.restigate the na.tur.e of the slJ.ver pre­cipit.􀍻te !rem the cy;r:iide solu·t:i.i,ns, !n prepa;.•i::lg a l􀎤ge (!\,wrttity ,:f the preci-pi t􀎶te 1 t. wa, fo·und that a.fter c,:.\i;:1 ete prEc"'.pi tat ion cf the eil ver the !IOl ution con ta.ined soluble eulphic.e 􀐉 • Thia p:!:'O'lided a el f!W "lt·d. a.ft er apr,ropri-9.te tests the preeipita.te VIO,I proved to 'be ailver sulphide.