Spent acid decomposition

Oxygen-enriched air is sometimes used in spent acid decomposition furnaces to increase furnace capacity. Use of oxygen-enriched air reduces the amount of inerts in the gas stream in the furnace and gas purification equipment. This permits higher SO2 throughput and helps both the heat and water... 

Metallurgical (smelter) plants and spent acid decomposition plants usually produce acid of good (low) color because the SO2 feed gases ate extensively purified prior to use. In some cases, however, and particularly at lead smelters, sufficient amounts of organic flotation agents are volatilized from sulfide ores to form brown or black acid. Such acid can be used in many applications, particularly for fertilizer production, without significant problems arising. 

Sulfur burning furnace Sulfide mineral smelters and roasters Spent acid decomposition furnace... 

Table 5.2. Operating details of 2 industrial spent acid decomposition furnaces.

Fig. 5.2. Spent acid decomposition furnace. It is brick lined steel 4 m diameter and 20 m long. The energy for decomposing H2S04(< ) into S02(g), 02(g) and H20(g) and for evaporating water is provided by burning molten sulfur and natural gas with hot air. Industrial details are given in Table 5.2.

Operating window for spent acid decomposition furnace (Outokumpu, 2004 Monsanto Enviro-Chem, 2005 Lang, 1998). Optimum temperature and 02-in-fumace-offgas ranges are suggested. 

Table 5.3 Details of spent acid decomposition furnace offgas cleaning and water condensation.

Fig. 6.2. Dehydration of metallurgical and spent acid decomposition furnace offgas. Dehydration is done after (i) H20(g) has been condensed by gas cooling and (ii) aqueous mist has been removed by electrostatic precipitation (not shown). The gas leaving dehydration contains 50 milligrams of H20(g) per Nm3 of gas. The acid plant s main blower is situated immediately after dehydration.

C02 is usually present in spent acid decomposition and metallurgical furnace offgases. Most of it passes through gas cooling/cleaning/dehydration and into the Fig. 10.1 catalyst bed. It doesn t take part in catalyst bed oxidation. 

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