Iron sponge process

The iron sponge process is very old (introduced in England in the mid-19th century) and very simple. It removes only H S and mercaptans. It is good only for streams containing low H2S concentrations at pressures of 25 to l,200psig. Hydrated iron oxide containing water and of proper pH is supported on wood chips or other material. Water is injected with the gas. 

The iron sponge process uses the ehemical reaction of ferric oxide with Hi.S to sweeten gas streams. This process is applied to gases with low H S concentrations (300 ppm) operating at low to moderate pressures (. vO-SOO psig). Carbon dioxide is not removed by this process. 

The ferric oxide is impregnated on wood chips, which produces a solid bed with a large ferric oxide surface area. Several grades of treated wood chips are available, based on iron oxide content. The most common grades are 6.5-, 9.0-, 15.0-, and 20-lb iron oxide/bushel. The chips are contained in a vessel, and sour gas flows through the bed and reacts with the ferric oxide. Figure 7-3 shows a typical vessel for the iron sponge process. 

The zinc oxide process is similar to the iron sponge process. It uses a solid bed of granular zinc oxide to react with the H2S to form water and zinc sulfide ... 

The SulfaTreat process also uses an iron-based scavenger for trace H2S removal. It has the advantage over the traditional iron sponge process of being non-pyrophoric. 

Slurrisweet Process. The Slurrisweet process was developed by Gas Sweetener Associates as a process that would utilize the same chemistry as the iron sponge process, but avoid... 

Schaack and Chan (1989) made both economic and qualitative comparisons of six different scavenging processes. Table 16-5 gives the results of their qualitative evaluation, which is intended to include both economics and operational characteristics. The Scavinox process scored highest in this analysis, but is no longer marketed under this name. A related proces.s, Di-Chem. which also appears to be commercially unavailable, scored third in the analysis, but appreciably below the second process, Sulfa-Check. The commonly used iron sponge process produced the lowest (worst) score. 

It is difficult to remove H2S to pipeline quality with a membrane sy stem. Membrane systems have effectively been used as a first step to remove the CO2 and most of the H2S. An iron sponge or other H2S treating process is then used to remove the remainder of the H2S. 

Iron Sponge Also called Dry box. An obsolete process for removing hydrogen sulfide from gas streams by reaction with iron oxide monohydrate. The ferric sulfide that is formed is periodically re-oxidized to regenerate ferric oxide and elemental sulfur. When this process becomes inefficient because of pore-blockage, the sulfur is either oxidized to sulfur dioxide for conversion to sulfuric acid, or is extracted with carbon disulfide. 

Let us take the example of iron oxide reduction in solid state by carbon monoxide, as it happens in the sponge iron making process. 

See iron oxide process iron sponge, spent. 

In summary, the WRS and BRS produce process water, vapor to the BRS OTS, and secondary waste in the form of a solid cake for shipment to an offsite TSDF. It is planned that the BRS OTS filter cake will be analyzed for toxicity characteristic leaching procedure (TCLP) organics (volatile and semivolatile constituents) and metals. In addition, the filter cake is planned to be tested for free liquids to ensure the dewatering has removed liquids in accordance with land disposal restrictions (PMACWA, 2006).25 The BRS OTS is, for the purposes of this report, identical to the BTA OTS except that there are no iron sponge absorbers or condensate pumps. The BRS OTS produces prefilter, HEPA, and charcoal filter secondary wastes. 

Direct reduced iron (DRI, sponge iron), metal powders, titanium sponge Processing of metal or metal-bearing wastes for recycling... 

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