Conventional sintering furnaces

Conventional Sintering Equipment. Like drying furnaces, sintering furnaces (29,76,85) can be periodic or continuous in nature. Periodic kilns offer greater flexibiHty continuous tunnel kilns are more economical. Advanced ceramics are typically siatered in high purity, controUed atmosphere furnaces by electric resistance heating. Ceramic furnaces used to fire traditional ceramic ware are generally heated with inexpensive natural gas, oil, wood, or coal. 

These studies, associated with pilot-plant trials, indicated that Sirosmelt technology, because of its flexibility, versatility and simplicity, was the most suitable process to replace the conventional sinter machine-blast furnace. The process has been optimized since the start-up of the furnace based on increased industrial experience and pilot plant trials at the Metaleurop Research Centre. Improved automation and expert systems are necessary to stabilize the process because of the short residence times involved. The bath smelting process operates with a large range of primary and secondary feed materials, and carries out different metallurgical operations in the same reactor.The exhaust gases produced are processed in a sulfuric acid plant, and final SO2 conversion efficiencies of more than 99.5 % are achieved. All the emissions have been drastically reduced CO2 emissions have decreased by 60 %. 

The operations in the Mt. Isa primary refinery have been covered by previous papers (2,6). The Mt. Isa bullion is produced by a conventional sinter plant/lead blast furnace operation. The resulting crude bullion is decopperised to less than 0.003 % Cu and is then given a caustic soda treatment to remove arsenic to less than 0.003%, prior to casting into 4-tonne slabs. This impure lead is shipped by railroad to Townsville and then by sea in 12,000- to 14,000-tonne shipments to BRM for further processing. 

Conventional blast furnace process. The graded sintered calcine obtained earlier is mixed with coke and limestone acting as flux and fed into the top of the blast furnace, where it is smelted using preheated air introduced at the bottom. The reduction processes yields a lead bullion, that is, an impure lead metal containing gold and silver as well as antimony, arsenic, copper, tin, and zinc. Lead bulhon is tapped off from the bottom of the furnace and either cast into ingots or collected molten in ladles for transfer to the refining process. 

IPS ERIS for E2 can be very homogeneously sintered in a conventional dental furnace at approximately 750°C. It shows a low residual porosity after firing. More than 99% of the theoretical density can be achieved. The low porosity content has considerable advantages with regard to the mechanical properties of the sintered product. IPS ERIS for E2 was developed by Ivoclar Vivadent AG (Liechtenstein). 

The new direct smelting processes have been attributed some general advantages over conventional sinter/blast furnace techniques ... 

The conventional industrial method for the synthesis of a-silicon carbide is to heat silica (sand) with coke in an electric furnace at 2,000-2,500 °C. However, because of the high melting point of the product, it is difficult to fabricate by sintering or melt techniques. Thus, the discovery of a lower temperature fabrication and synthesis route to silicon carbide by Yajima and coworkers in 197526,27 proved to be an important technological breakthrough. This is a preceramic polymer pyrolysis route that has been developed commercially for the production of ceramic fibers. 

Although means are available for controlling the bulk of the emissions from the conventional lead and zinc smelters, new processes being developed offer greater economy as well as better emission control (9,10). Cominco Ltd. recently announced the development of a new process to replace the conventional lead smelting process with its sintering plants and blast furnaces (39). 

Fig. 4.14. Traveling grate furnace for roasting, sintering, or pelletizing ores. The ignition arch or hood may be fired with conventional type A flames or flat type E flames (shown, see fig. 6.2.)...

The roast-reduction process using Dwight-Lloyd sinter machine and blast furnace operation is still the basis for the majority of the lead produced in primary smelters. Since the last survey (1), however, the total number of smelters based on this conventional technology has been remarkably reduced. 

The lead plant in Nordenham used the conventional two-stage sinter machine-blast furnace process until the development of bath smelting technology in 19%. 

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