Furnace fumes

Black liquor recovery furnace fume Venturi and cyclonic spray 1.75 0.620... 

Open-hearth steel furnace fume Venturi 1.26 0.569... 

Coming out of the furnace, fumed silicas are obtained in a fluffy form, and because of their high temperature of formation, they present a very stable morphology and few surface silanols compared to precipitation silicas. This confers a high dispersibility and reactivity to fumed silicas but, because of their higher price, they are rarely used in the rubber industry. 

The energy recovery from furnace fumes and gases is around 20 % of electrical energy input in modem furnaces. It can be enhanced to close to 100% if low-temperature energy can be... 

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. 

In the electrothermic part of the furnace, electrical energy introduced via three carbon electrodes, keeps the bath molten and completes the lead oxide reduction. Fumes generated in the electrothermic section are oxidized in a post-combustion chamber by adding ambient air, before the vapor is cooled, dedusted, and released to the atmosphere. 

However, rotary furnaces tend to produce more exhaust gas and fumes, require more skill fill manipulation, and are more labor intensive. Also, the slags produced in the rotary furnaces, soda or fayaUte [13918-37-1] slags, normally do not pass the toxic characteristic leach procedure (TCLP) test and pose a disposal problem. 

A 75% ferroshicon furnace operating at 90% shicon recovery would give 0.24 kg of by-product shica fume per kg of shicon produced. A shicon metal furnace operating at 85% recovery (typical of the iadustry) would give 0.38 kg of fume shica per kg shicon produced. 

Fuming is also an alternative to roasting in the processing of low grade concentrates (5—25 wt % tin). This procedure yields a tin oxide dust, free of iron, which is again fed back to a conventional smelting furnace. 

Batch Process. In the batch process (Fig. 5), the feedstock is preheated in a tube furnace or heater placed between the feedstock storage and the blowing vessel. The air supply is provided by a variety of blowers or compressors and a vertical-tower vessel is preferable for air-blowing. Knockout dmms, water scmbbers, incinerators, furnaces, and catalytic burning units have been used for fume disposal (32). Steam is used for safety and to ensure positive fume flow to the incinerator. 

The ziac concentrate is first roasted ia a fluid-bed roaster to convert the ziac sulfide to the oxide and a small amount of sulfate. Normally, roasting is carried out with an excess of oxygen below 1000°C so that comparatively Htfle cadmium is eliminated from the calciaed material ia this operation (3). Siace the advent of the Imperial Smelting Ziac Furnace, the preliminary roasting processes for ziac and ziac-lead concentrates result ia cadmium recovery as precipitates from solution or as cadmium—lead fume, respectively, as shown ia Figure 1. 

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