Refinery slag

Eisen-feilicht, n., -feile, /. -feilspaUe, m.pl. iron filings, -feilstaub, m. fine iron filings, -feinschlacke, /. iron refinery slag, -firms, m. varnish for iron, -fiasche, /. iron cylinder (for gases), -fieck, m. iron spot, iron stain. 

Fein-schlacke, /. refinery slag, -schlag, m. fines. 

The by-products produced in all these processes are liquation residues, matte, slags, refinery slags, and flue dust. They are added to the charges in smelting the ore, if they are sufficiently rich the liquation dross, however, is subjected to a preliminary roasting, and the flue dust is intimately mixed with lime, before smelting. Liquation residues are also sometimes treated separately in shaft furnaces. 

Refinery slag generally contains from 20 to 60 per cent, of antimony, and is a mixture of soda, sodium sulphantimaaiate, antimony trioxide and tetroxide, ferrous oxide, iron sulphide, arsenic oxide, and smaller proportions of silica and alumina it is added to charges of ore. 

Wet Process. The sodium arsenate and stannate slag are treated by a leach and precipitation process to produce calcium arsenate, calcium stannate, and a sodium hydroxide solution for recycle. The sodium antimonate filtercake containing selenium, tellurium, and indium is treated in a special metals refinery to recover indium and tellurium. 

In 1986 Britannia Refined Metals (Northfleet, U.K.) introduced technology for the treatment of Parkes cmst, a triple alloy of Ag, Zn, Pb, which by 1992 had been adopted by seven lead refineries (22). The technology consists of a three-stage process in which the silver-rich cmst is first Hquated to reduce its lead content, then placed in a sealed furnace where the 2inc is removed by vacuum distillation and, finally, the silver—lead metal is treated in a bottom blown oxygen cupel (BBOC) to produce a Htharge slag and dorn metal. 

Tellurium is stUl recovered in some copper refineries by the smelting of slimes and the subsequent leaching of soda slags which contain both selenium and tellurium. The caustic slags are leached in water and, using the controlled neutralization process, tellurium is recovered as tellurium dioxide. 

Because of the high tin content of the slag, a primary smelting is used to effect a first separation, followed by a second stage to process the slag and hardhead from the first smelting plus refinery drosses. 

The removal of small quantities of arsenic from metals and ores is a commercial problem which may be mentioned at this point. The Harris process of softening lead,6 used in several refineries, is based on the principle that such impurities as arsenic, antimony and tin may easily be oxidised and in the presence of certain alkali salts can he converted into arsenates, antimonates and stannates. Certain fluxes, such as sodium nitrate, sodium hydroxide, sodium chloride or lead oxide, are added to the molten lead, the presence of an oxidising agent and an alkali salt being essential. The alkaline slag obtained is fused 7 and... 

At the Societe le Nickel refinery in Le Havre, France,193 a solution obtained from the leaching of a chlorinated nickel slag and containing 56 g of nickel, 22 g of cobalt and 36 g of iron per litre in 7.5 M chloride is first treated with a 0.3 M solution of the secondary amine Amberlite LA-2 in an aromatic solvent to remove the iron ... 

The lead is transferred from the CDF to a series of induction-heated steel pots, a softener, and then to a continuous sulphur drossing circuit (CSD). The softener controls the antimony and arsenie at 1.2% and 0.7%, respectively. The remaining copper from the CDF is reduced to less than 0.005% in the CSD. The lead bullion is cast into 3-torme buttons for shipment to the lead refinery. The copper matte and softener slag are treated in downstream plants. 

Lead bullion is clectrorcfined to produce refined lead and slimes. The slimes arc treated in the silver refinery where a series of furnaces process the slimes to produce dore metal and bismuth, as well as various slags and baghouse dusts that contain antimony and arsenic. Some of the baghouse dust is directed to the copper products plant and the lead alloys plant to recover antimony and arsenic values, and the remainder of the baghouse dust and the slags are recycled to the smelter. Done metal is electrorefined to produce pure silver and gold bullion. 

Also included in Lead Operations are a lead allo3rs plant, a copper products plant, and an effluent treatment plant. The lead alloys plant produces arsenic-lead and antimony-lead alloys from the treatment of softener slag and silver refinery baghouse dust. The copper products plant produces copper sulphate, copper arsenate and sodium antimonate fi"om the treatment of copper matte and refinery baghouse dusts. The effluent treatment plant treats effluents from the zinc and lead operations as well as surface runoff from throughout the metallurgical operation. 

Mineral Wool Mineral wool is a low-cost silicate fiber spun from molten slag in steel refineries. It is widely used as thermal insulation in housing and apphances. Since its composition and structure are not well controlled, it is not comparable with chopped glass fibers however, it is sometimes used as a partial replacement for them. Jim Walters Processed Mineral Fiber (PMF) in particular has been reported for such apphcations. 

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