Sulfur wallboard

A typical sulfur wallboard sample had a density of approximately 0.5 g/cc as compared with 0.9 g/cc for plaster board. It was also evident that the sulfur board was considerably stronger than the plaster board even though strength tests were not conducted. Plaster board was easily broken by hand whereas much more physical exertion was required to break the sulfur board. 

A section of sulfur wallboard is presented in Figure 8. It is able to accept nails and screws, which is important to this application. While tests have not been conducted on the noise and thermal insulating characteristics of the sulfur board, there is no reason to doubt their adequacy. 

As indicated earlier, the unpleasant odors created by organic reaction products pose a serious problem, especially with sulfur wallboard because it would be used in a confined area inside a building. The foam may be made rigid by other means which do not create unfavorable reactions. Another approach is to use hollow glass beads or expanded lightweight aggregate bonded by the sulfur instead of foaming the sulfur. This would eliminate the need for the phosphorus pentasulfide-styrene additives which are one of the causes of the odor. 

Figure 9. Schematic of proposed continuous sulfur wallboard production...

An important technology for removal of S02 is Flue Gas Desulfurization (FGD), carried out in units known as scrubbers. Most scrubbers contact the flue gas with a slurry of lime or limestone to capture the sulfur oxides and produce a sludge containing calcium sulfite and calcium sulfate. However, disposal of sludge is another environmental problem, and some scrubbers include oxidation to convert all the calcium sulfite to sulfate (gypsum), which can be used for wallboard manufacture. Fluidized-bed combustion units add a sulfur... 

Flue gas desulfurization systems are classifled in two general categories. One group involves throwaway product systems where sulfur product (untreated or treated) is disposed of as a landfill. The other group produces saleable products such as sulfuric acid, elemental sulfur or, as in Japan, gypsum for wallboard and sodium sulfite for paper mills. 

Molten sulfur was developed into a lightweight wallboard material because it can be foamed. Just above its melting point of 115°C sulfur viscosity decreases to a minimum at approximately 160°C. Above 160°C the viscosity increases rapidly (4). To foam the sulfur at the lower part of this temperature range, additives are required which prevent the foamed structure from collapsing. Additives such as phosphorus penta-sulfide and styrene monomer have been developed by Southwest Research... 

Using this formulation, a process was then developed to produce lightweight wallboard. The surfaces of the foamed board were compressed or densified to produce relatively high smoothness. Paper sheets normally used to cover wallboard were applied to both sides simultaneously with the compression action. The excellent adhesive character of the sulfur produced tight bonding, and no special treatment of the paper was required. 

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