Cobalt Slag

WildlarkDr., Peterborough, Ontario, K9K 2J4, Canada Keywords Recycling cobalt, spent batteries, spent catalysts, cobalt slag. 

In addition, molybdenum has high resistance to a number of alloys of these metals and also to copper, gold, and silver. Among the molten metals that severely attack molybdenum are tin (at 1000°C), aluminum, nickel, iron, and cobalt. Molybdenum has moderately good resistance to molten zinc, but a molybdenum—30% tungsten alloy is practically completely resistant to molten zinc at temperatures up to 800°C. Molybdenum metal is substantially resistant to many types of molten glass and to most nonferrous slags. It is also resistant to hquid sulfur up to 440°C. 

Single-wall tubes. Following the synthesis studies of stuffed nanocapsules, single-wall (SW) tubes were discovered in 1993(9,10]. SW tubes are found in chamber soot when iron[9] and cobalt[10] were used as catalysts, and for nickelfl 1,40] they grow on the surface of the cathode slag. For iron catalyst. 

The production of cobalt is usually subsidiary to that of copper or nickel and the methods employed differ widely, depending on which of these it is associated with. In general the ore is subjected to appropriate roasting treatment so as to remove gangue material as a slag and produce a speiss of mixed metal and oxides. In the case of arsenical ores, AS2O6 is condensed and provides a valuable byproduct. In the case of copper ores, the primary process... 

The carbides are generally not resistant to molten slags and fused salts. Their resistance to molten metal is usually poor. For instance, TiC is attacked by nickel, cobalt, chromium, and silicon. SiC is attacked by aluminum. 

As mentioned above, approximately 7% of the total sulfur present in lead ore is emitted as S02. The remainder is captured by the blast furnace slag. The blast furnace slag is composed primarily of iron and silicon oxides, as well as aluminum and calcium oxides. Other metals may also be present in smaller amounts, including antimony, arsenic, beryllium, cadmium, chromium, cobalt, copper, lead, manganese, mercury, molybdenum, silver, and zinc. This blast furnace slag is either recycled back into the process or disposed of in piles on site. About 50 to 60% of the recovery furnace output is slag and residual lead, which are both returned to the blast furnace. The remainder of this dross furnace output is sold to copper smelters for recovery of the copper and other precious metals. 

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 ore is crushed and ground in.ball mills to pass through a 30-mesh sieve. It is mixed with suitable fluxes (limestone and quartz) and smelted in small blast-furnaces having a capacity of 25 to 30 tons per twenty-four hours. The products obtained are (i) flue dust, which is returned to the furnaces, and crude arsenious oxide, which is resublimed and sold (ii) a silicate slag, which is thrown away unless it contains more than 10 ounces of silver per ton (iii) crude silver bullion, which is mechanically detached and cupelled to a fineness of 994 before it is sold to silver refiners and (iv) a speiss of cobalt, nickel, iron, and copper arsenides, containing considerable amounts of silver. The crude silver bullion contains about three-fourths of the silver present in the ore. 

The residue from the chloridised speiss, after extraction of soluble cobalt and nickel salts, is extracted with sodium thiosulphate, to dissolve out silver chloride, which is recovered as the sulphide and reduced to metal. The residue is dried, ground, and smelted with quartz to remove most of the iron as a slag. This slag is reworked with more ore in the blast-furnaces, as it contains silver and cobalt. The new speiss simultaneoiisly produced is treated as described above for recovering cobalt and nickel, copper, and silver. The final residue is dried, mixed with 20 per cent, of sodium nitrate and 10 per cent, of sodium carbonate, and roasted in reverberatory furnace to convert the arsenic into sodium arsenate, which is extracted with hot water. The dried residue has the following average composition ... 

The decomposition of the lower sulfides of the heavy metals and the recovery of the metal as soluble salts and of sulfur in the elemental form have been demonstrated for pyrite, pyrrhotite, chalcopyrite, sphalerite, galena, molybdenite, and associated metals such as nickel and cobalt. Pyrite and chalcopyrite are higher sulfides and to be amenable to this treatment have to be thermally decomposed at 600-650 C prior to leaching. The reactions with nitric acid are exothermic, and are carried out below 1 atm and at around 100°C. In addition to the sulfides, this technique has been applied successfully to the extraction of nonferrous metals from partly oxidized sulfide ores, fayalite slags, copper scrap, and other intermediate products, such as residue from electrolytic zinc plats. 

Cobalt (4 X 10 % of the earth s crust) occurs principally as smaltite, C0AS2, and cobaltite, CoAsS. The metal is used in corrosion-resistant alloys and magnets. Smelting involves oxidation of the ore to C03O4, iron and arsenic being removed as slag, followed by alumino-thermic reduction of the cobalt oxide ... 

Figure 13. Simplified process flowsheet to recycle cobalt from slag in Zambia (Chambishi)...

---