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Show The Story of Milling and Smelling at Midvale - in rr iiiniii'i'iiii' wirw hihuh' NniiiTnwffWWwnrTnnTWTT i VMMMM t ... jw-v rrz . :: i ".-'l --i ,-."- -i:---.v;. V: .;-. . -r.'-. ; -r '.:l " -k .5.;. . )-: a' - . f : - v- , ;' v" vi , , ! i h v ' s ' !. . ' .; , ' " ' . , . ft and leaving the lighter material at the bottom. . j . - (E.lilor'8 Not: Thu is the third of ierie uf fiv urtick-s on the story of mill-nd mill-nd smelting of Jead-ainc oi-e t Midvale.) ' Tlie lirrvious article of this scries lnt'iUiiuiwl tlu- itiiportauce of flit"' . : discovery uu.l application of tlie flolation pitucss for he recovery of zinc, previously a. penalty, ele-ment ele-ment iji. l-ad-zine siriphid' oVes. There is rjnuince in "the evohi-, evohi-, . . . . Hon, of fiwtrrUmi. It was conimon ksowlotlRe rhat substances heavier tfian watr would, under certain 8ui(able-p.tdit.)B8, float on the wa-ter'sstwface, wa-ter'sstwface, tar example, a greased or dry needle carefully pluced on - water. )t has beea known for years ' . that some heavy substances will float with more certaiity than Othprs. It is reported that about ' 1 8 8 Carrie J: Kverson, a western lady school teacher, assisting in her brother's Denver assay pfflce, ,dis- covered themaln iwinciples on which all subseauenTTTotaTOn work baa been based. She had placed ome greasy concentrate sacks in th wash lub and with the washing : (ore bags are-rarely, if ever, washed by men) the germ of the idea of oil flotation came under her observa- tlon. . , Modern flotation is a concentrat ing process utilizing' the .buoyancy of air bubbles in water to "float" mineral particles. Certain reagents or'Frotliers" are used to strengthen strength-en the biihbk's thus forming a sirtmg unci persistent froth simtliar to soap suds. Other rva gouts known as "CoHeetors" and "Modiliers" aru i;s("(l to -condition the mineral Var-ticles Var-ticles so that they will or will not aniiere to the air bubliles. , 'I his permits' Selec'tiTity ia the flofatiou of oue or ninfe aiinerals fi'osi 'mixture -of .minerals as they oct-ifl-in natuml ore. ; ,TTie.U'e fom aompany mines and c'nsto shipjHus.' receivecLat M-Ulvsle Plant of. Knited St;cJ Smelting Ketining and Mining conT pany is weighed in railroad cars and then goes to the sampling department de-partment where an accurate and representative small sample is automatically taken. The sample thus taken is ground to fine powder -gird one part of tfre-gaiylo goonta the shipper. Midvale assay of metal content determines whether the ore goes to the flotation mill or direct to the smelter. : After weighing and sampling the ore for the flotation, mill it Is sent through a series of crushing, grinding grind-ing and regrinding units until Anal ly approximately 657e ot tae ore pulp will pass through a wire mesh gcreen having 40,000 openings to the square im-h. This fine pulp reaches the flota-' tlon machines, where , witji certain reagents added the lead minerals float while the. other minerals sink. The lead float (concentrate) Is skimmed off Hie surface ,of the notation cells aad the residue, after addition of o,t'hnr chetntrals goos, to the line flstation mat-airies whore tb line mitftral floats and Ts" fcliuimed off as zftic eaneawtratfl. Other concenvrates of resser-ire portance ars madoftis (arcUrastanoes warrant airtfough it is neyer possible pos-sible to recover all the minerals in an ore. As in the case of the floating float-ing needle having a dry or greased surface, particles, of ore attach themselves to' air bubbles even below be-low the surface of te water as these bubbles are forced through -tfre flotation marhlna cells along with the chemicals. " The flotation concentrates are Wwatered in 50-foot thickeners and mostof the remaining water Is Uien removed ihIters.Tifter whlcnth lead concentrate is transported to "the lead smelter and the sine concentrate con-centrate shipped to a inc plant. r.". ' ."HE FOURTH OF THESS ARTICLES WILL. APPEAR BOON.) : : - - i ' : ; : : " " ' |
