Show the leacha leaching e ng plant at ludwig BY GEORGE gurgu WESTBY the leaching plant with the exception of the apparatus used in decomposing sulphide ore represents either a development of successful experiments instituted by the company or an adaptation of current practice to the peculiar requirements of the ore in many ways the plant is unique yet no part is painfully new the salient peculiarities are the processes through which the solvents used in the treatment of the ore are regenerated and the arrangements providing continuous treatment of the gr greater 1 e a ter part of the ore passed through the mill general practice is followed in the crushing mill arrangements the application of industrial metallurgy and the means of handling solutions and washing the residues the general procedure is as follows the ore received from the mines is weighed on track scales and then discharged to coarse ore bins by means of self sel dumping ore cars A conveyor belt trans fers the ore from the bin to the coarse crusher which breaks the ore to sizes approximately the 1 inch cubes or smaller coarse crusher as a feeder discharges to the intermediate crusher which in turn dis charges to an ail elevator the elevated material is passed over screens the oversized returning to the intermediate crusher and the undersized passing to vertical rolls process is used again as a solvent of oxidized ores in connection with the use of hot acid fumes derived from wedge furnaces the residue or tailings are discharged with sufficient water to carry them well away from the mill Y I 1 jr it P 7 44 bw 17 al 11 atz 4 aa aa view of the new milling plant of the Nevada Douglas consolidated copper company which are designed to crush the material to 15 mesh or finer the discharge from the rolls is elevated and passed through screens the oversize returning to the rolls and the undersize to either of two fine ore bins depending on whether the ore is sulphide or oxidized the fine ore leaves the crushing plant in two streams the sulphide ore is conveyed to the chemical building and discharged to an ore bin located above what is known as a dig digester estor wherein the decomposition of the sulphide ore is brought about the oxidized ore is discharged continuously from the bin to a series of closed pachuca like tanks for treatment the sul bhide ore is intermittently charged into strong nitric acid contained in the the intense chemical action involving the evolution of much heat and the decomposition of the sulphides sulp hides is at on once ce set up the result of the reaction is practically speaking the production of sulphate of copper an and d iron with the formation of nitric oxides ti the ie nitric oxides escape into absorption towers containing an excess of water and are thus re converted into nitric acid which may y again be used in the process the solution containing the sulphates is together with the residue discharged to a receiving I 1 tank from which it is caused to pass into a system of replacement tanks and filters aich which separate the clari clarified fid solution from t the line washed residues the solution in the the oxidized ores are by means of a belt feeder charged to a pacu pacucha clia tank into wl which aich a acid solutions derived from the sul I 1 bhide treatment as described are flowing the agitation of the mass and the entering t i d I 1 A t 0 w g R 14 consolidated photo by will C higgins Hi gins douglas nevada 31 head frame at ludwig mine solutions carry the dissolving ore f from rom tank to tank through the series until it finally falls into the replacement tanks following the course of the residues from crom the diges tor Suppler supplementing the action of the solutions and in fa fact ail t supplying the principal f J active reagent in the treatment of the oxidized ores are the sulphurous fumes produced in a succeeding operation th fumes are caused to flow inside a wooden chamber filled with staggered pieces arranged longitudinally along the tops of the pach the mixed ore and solutions are raised by an air lift and are sprayed over distributing boxes at the top of the fume chamber the mixture then falls in cascading sheets through the ac acrid rid fumes bringing about an active solution of the copper and iron in the ore and causing a practically complete absorption of the fumes the combined solutions after separation odthe of the solids are pumped to a refinery where the greater part of the copper is economically extracted from the liquid by electrolysis the residual solutions heavily with iron salts are passed over scrap iron which removes almost the last traces of copper the iron charged liquors are lifted by means of a pump to the top of an evaporator through which they fall in broken films to tanks below becoming in their descent a fluid mass of fine crystals which fall through the mother liquor to the bottom of the tank situated beneath the evaporator A drag conveyor pulls the crys atals into a drainage channel and finally discharges the crystalline mass to a chute end ing in the hoppers li of a set of dryers in their passage through the dryers the crystals are dehydrated and heated preparatory to their treatment in the furnaces the heated crystals are carried from the dryers by means of a conveyor which discharges to the hoppers of the furnaces the furnaces complete the cycle of operation by decomposing the crystals into the acid fume which react again on fresh batches of ore leaving as a residue as a product byproduct by a material which forms the base of an excellent paint |