Sinter feed

The Utah deposit is located in southwestern Utah near Cedar City. The iron ore deposits are of contact metamorphic origin. The cmde ore contains 35 to 65% iron, primarily in the form of magnetite and goethite. Mining is done by the open pit method. The cmde ore is cmshed, screened at —75 mm (—200 mesh size) and shipped as lump ore containing 54% iron. The ore is rescreened at the steel mill to produce lump ore (10—64 mm) for the blast furnace and sinter feed (0—10 mm) for the sinter plant. 

When fines are recycled, as in iron ore, sinter feed, or fertilizer drum granulation, they are rapidly granulated and removed from the... 

Sintered feed Zn0+Pb0+Fe203 +Ce0+Si02 Pre-heated coke at 800° C... 

The Japanese Direct Iron Ore Smelting (DIOS) process. This process produces molten iron directly with coal and sinter feed ore. A 500 ton per day pilot plant was started up in October, 1993 and the designed production rates were attained as a short term average. Data generated is being used to determine economic feasibility on a commercial scale. 

Some cokeless technologies in use or under development include the Japanese direct iron ore smelting (DIOS) process, in which molten iron is produced directly with coal and sinter feed ore, the HIsmelt process, where ore fines and coal are used to achieve a production rate of 8 t/h using ore directly in the smelter, and the Corex process, which has an integral coal desulfurizing step, making it amenable to a variety of coal types.14... 

When fines are recycled as in iron ore sinter feed or fertihzer drum granulation, fines are rapidly granulated and removed from the distribution up to some critical size, which is a function of both moisture content and binder viscosity. Changing the initial-size distribution changes the granule porosity and hence moisture requirements [Adetayo et al., Chem. Eng. Sci., 48, 3951 (1993)]. Since recycle rates in drum systems are high, differences in size distribution between feed and recycle streams are one source of the limit cycle behavior observed in practice. 

Of the 20 plants surveyed, 8 operated smelters with S having a sinter feed and 3 a briquette feed. Table Vn gives the operational data for the smelters. 

In practice, for the sintering of lead sulfide concentrates, a sulfide sulfur content of the charge of around six to seven per cent is required to achieve the necessary peak bed tanperature. Since lead concentrates normally range from 15 per cent to 25 per cent sulfide sulfur they must either be diluted or partially roasted before sintering. Some dilution with return material occurs, but dilution with recycled sinter is the preferred approach because of the high degree of control over the sinter feed mix... 

Reduced levels of return sinter will cause a decrease in bed permeabihty, reducing possible gas flow and hence, sinter machine capacity. On the other hand gas permeability is enhanced by increased levels of return sinter, but fuel value of the charge is reduced and peak bed temperature is lowered. This leads to poorer quality sinter with increased fines, which report to returns and reduce sinter bed permeability, thus reducing gas flow and machine capacity. The product sinter in this case is also weak and readily breaks up in the shaft of the blast furnace, reducing permeability and blast furnace throughput. Hence, there is an optimum level of recycle sinter and of fuel to maximise sinter machine capacity. This normally corresponds to a sulfide sulfur content of sinter feed of six to seven per cent and a minimum recycle ratio of 1 1 (recycle net sinter production), or 50 per cent of total sinter production. 

Measurement of the moisture content of sinter feed with feedback to direct water additions at various mixing points is thus an essential part of good sinter machine control. Various devices are used for online moisture measurement, including infrared devices and electrical conductivity probes. The latter are most common and can simply be two trailing electrodes in contact with the feed material on a conveyor belt. These devices are not highly reliable and need careful and regular calibration since they are affected by the presence of soluble salts, which can change the electrical conductivity of the free interstitial water in the sinter bed. 

Collected dusts are commonly pulped in water for ease of handling, and are filtered and the filter cake combined with dusts collected from sinter plant combustion gases and blast furnace fumes for return to the sinter feed mixing facility. The total load of collected dusts can be up to 2.5 per cent of total sinter production, and the volume of ventilation gases for the sintering operation can be of the order of 1500 Nm /h/m of sinter plant grate area. 

The use of oxygen enrichment of sinter plant air feed has been evaluated as a means of increasing machine capacity in terms of the sulfur elimination rate. It is debatable whether there is any benefit, since excessive bed temperatures must be avoided, requiring a reduction in the fuel content of sinter feed and hence, lead sulfide feed. However, even if there were some benefit, oxygen is used in considerable excess and inefficiently for sulfur combustion. On this basis alone enrichment is generally not economically justified. 

For a given sinter feed and blast rate, the operating parameters relating to fnel which affect furnace performance are ... 

Coke will usually add significant quantities of sihca (up to 50 per ceut of sinter feed amounts) and will alter these ratios for blast furnace slag, which is the ultimate target. 

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