Sulfide primary smelting

Production of matte. A few secondary smelters form a matte, a high sulfide material generally containing arsenic, to remove unwanted elements. This process is common in primary smelting. 

Sulfide ores are usually concentrated by mechanical upgrading and flotation processes at the mine. The nickel concentrate is then transported to the refinery for py-rometallurgical treatment j fter a roasting, to drive off part of the sulfur as sulfur dioxide SOj, the material is melted with a siliceous flux. This primary smelting forms two liquid phases, one a sihcate slag and one a sulfide phase, a low-grade matte, containing nickel and copper but also some iron. 

Some very unique opportunities are also exclusively available to the primary metals industry. For example, the use of dry air control devices and dry cast quench operations have been adopted at some facilities to avoid the generation of contaminated wastewater. Additionally, many facilities are finding markets for byproducts (e.g., sulfides resulting from nonferrous smelting operations can be converted to sulfuric acid and subsequently sold) which avoids the need to discharge these contaminants.24 25... 

Kraft pulp mills Digesters batch and continuous Multiple-effect evaporators Recovery furnace Weak and strong black-liquor oxidation Smelt tanks Lime kiln Mercaptans, methanol (odors) H2S, other odors H2S, mercaptans, organic sulfides, and disulfides h2s Particulates (mist or dust) Particulates (dust), H2S Condensers and use of lime kiln, boiler, or furnaces as afterburners Caustic scrubbing and thermal oxidation of noncondensables Proper combustion controls for fluctuating load and unrestricted primary and secondary air flow to furnace and dry-bottom electrostatic precipitator noncontact evaporator Packed tower and cyclone Demisters, venturi, packed tower, or impingement-type scrubbers Venturi scrubbers... 

All the platinum group metals are isolated from platinum concentrates which are commonly obtained either from anode slimes in the electrolytic refining of nickel and copper, or as converter matte from the smelting of sulfide ores. The details of the procedure used differ from location to location and depend on the composition of the concentrate. Classical methods of separation, relying on selective precipitation, are still widely employed but solvent extraction and ion exchange techniques are increasingly being introduced to effect the primary separations (p. i 147). 

Impure nickel, refined by smelting sulfide ores in a blast furnace, can be converted into metal from 99.90% to 99.99% purity by the Mond process. The primary reaction involved in the Mond process is... 

There are many different high temperature environments in a recovery boiler [2/0]. On the fireside of the boiler there is the molten smelt and the char bed in the bottom of the boiler. There is an oxidizing environment in the lower furnace where air is injected at up to four elevations for the combustion of the heavy black hquor that is sprayed into the boiler. Waterwall tubes are normally subjected to sulfidation. The use of composite tubes in the lower waterwalls has been successful in resisting sulfidation. The lower waterwall tubes may also have liquor running down them. At primary and secondary air ports, there are local environments that promote preferential corrosion and cracking of composite tubes. 

Primary lead smelting is largely based on the treatment of lead sulfide (galena) concentrates. A number of processes are used but the traditional sinter plant-blast furnace technology (as illnstrated in Figure 1.4) has predominated. 

The flotation process was developed in Australia at the turn of the century to treat the primary sulfidic silver/lead/zinc ore at Broken Hill, New South Wales, following the mining of the overlying secondary ore. Oxidation to form the secondary zone had resulted in a concentration of silver and lead, and this section of the ore body could be smelted directly. The underlying sulfide zone, which comprised the bulk of the resource, was less amenable to treatment in the smelters of that era, and a method was required to recover the zinc values if the potentiality of the primary ore was to be realized. Many approaches were pursued to solve the sulfide problem before selective flotation was developed. The flotation process was then rapidly adopted by mining companies throughout the world. 

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