Shaft furnace processes

The Imperial Smelting Process (ISP) technology is a modified variant of the conventional shaft furnace process, that is particularly suited to the treatment of bulk lead-zinc concentrates. The IS process was developed in the late 1950s by Commonwealth Smelting Ltd at its Avonmouth plant in... 

The description given apphes to DR processes that are based on the use of gaseous reductants ia shaft furnaces, batch retorts, and fluidized beds. In the processes that use sohd reductants, eg, coal (qv), the reduction is accomphshed to a minor extent first by volatiles and reduciag gases that are released as the coal is heated and then by CO that is formed by gasification of fixed carbon contained ia the coal char with CO2. Reductioa by sohd carboa and coal volatiles ia kilns is insignificant. 

MIDREX Process. The primary components of a MID REX process plant include the shaft furnace, reformer, and heat recuperator. These components are supported by ancillary systems for handling iron ore, gas, water, and direct reduced iron. A flow sheet is shown in Figure 1. 

Other DR Processes. The other DR processes, eg, the CODIR, DRC, ACCAR, and Dav Steel processes, make up 4.4% of worldwide production and mosdy consist of coal-based, rotary-kiln processes. Ah of these are similar to the SL/RN process. In addition, one small coal-based, shaft-furnace plant based on the Kinglor-Metor process is operating. 

Low Temperature Carbonization. The Lurgi Sptlgas process was developed to carbonize brown coal at relatively low temperatures to produce tars and oils (Fig. 5). A shaft furnace internally heated by process-derived fuel gas (Spblgas) is used. The product can range from a friable coke breeze to hard lump coal depending on the quality of the briquettes used in the feed. The briquettes, made in normal extmsion presses, break down into smaller sizes during carbonization. 

Batch Furnaces This type of furnace is employed mainly for the heat treatment of metals and for the drying and calcination or ceramic articles. In the chemical process industry, batch furnaces may be used for the same purposes as batch-tray and truck dryers when the drying or process temperature exceeds 600 K (620°F). They are employed also for small-batch calcinations, thermal decompositions, and other chemical reactions which, on a larger scale, are performed in rotary Idlns, hearth furnaces, and shaft furnaces. 

An improved approach from the point of view of thermal efficiency is the electrothermal process in which the mixture of zinc oxide and carbon, in the form of briquettes, are heated in a vertical shaft furnace using the electrical resistance of the briquettes to allow for internal electrical heating. The zinc vapour and CO(g) which are evolved are passed tluough a separate condenser, the carbon monoxide being subsequently oxidized in air. 

Three different types of furnaces are generally in use for calcination. The shaft furnace is considered to be the most suited for calcining coarse limestone. Furnaces of the rotary kiln type are used for handling materials of mixed particle sizes and lumps which disintegrate during the process. Calcination can be carried out in a fluidized bed-reactor for materials of small and uniform particle size. These furnaces are usually fired with gas, oil or coke in some cases electric heating is resorted to. 

The cathodes removed from the electrolytic cell are the primary product of the copper producer and contain >99.99% copper. These may be sold to wire-rod mills as cathodes or processed further to a product called rod. In manufacturing rod, cathodes are melted in a shaft furnace and the molten copper is poured onto a casting wheel to form a bar suitable for rolling into a 3/8-in.-diameter continuous rod. This rod product is shipped to wire mills, where it is extruded into various sizes of copper wire. 

Andco-Torrax A process for making a fuel gas by the partial oxidation of organic wastes in a vertical shaft furnace. The residue is removed as a liquid slag from the base of the furnace. 

COREX A two-stage ironmaking process. Iron ore is reduced in a vertical shaft furnace and then melted in a melter gasifier, which also generates reducing gases for the shaft furnace. Developed by DVAI, Dtisseldorf, and first used in 1989 at the Pretoria works of Iscor, South Africa. Ten plants were being planned in 1997. 

Otto-Rummel A coal-gasification process based on a double shaft furnace, developed in Germany by Dr. C. Otto Company. 

Purox A process for partially combusting organic wastes in a shaft furnace with oxygen, thereby producing a fuel gas and a molten slag. The gas, not diluted with nitrogen, is suitable for use as a chemical feedstock. Developed by Union Carbide Corporation in 1974 and piloted in Charleston, WV. 

SKF A DR process for making iron. Powdered iron ore and coal are injected through a plasma arc heater into a vertical shaft furnace. See DR. 

In an alternate process, a variation of the above method, molten lead is atomized in a shaft furnace. An air stream carries the very finely divided metal into the hot zone of the shaft furnace where the metal evaporates and oxidizes producing very finely divided lead monoxide. The product is passed... 

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