Sulfur mixing

Fresh reducing gas is generated by reforming natural gas with steam. The natural gas is heated in a recuperator, desulfurized to less than 1 ppm sulfur, mixed with superheated steam, further preheated to 620°C in another recuperator, then reformed in alloy tubes filled with nickel-based catalyst at a temperature of 830°C. The reformed gas is quenched to remove water vapor, mixed with clean recycled top gas from the shaft furnace, reheated to 925°C in an indirect fired heater, and injected into the shaft furnace. For high (above 92%) metallization a CO2 removal unit is added in the top gas recycle line in order to upgrade the quaUty of the recycled top gas and reducing gas. 

Methane reacts with sulfur (an active nonmetal element of group 6A) at high temperatures to produce carbon disulfide. The reaction is endothermic, and an activation energy of approximately 160 KJ is required. Activated alumina or clay is used as the catalyst at approximately 675°C and 2 atmospheres. The process starts by vaporizing pure sulfur, mixing it with methane, and passing the mixture over the alumina catalyst. The reaction could be represented as ... 

Figure 3. Marshall stability as a function of sulfur and asphalt contents in sand-asphalt-sulfur mixes (15,). Materials used were medium-coarse sand and 150/180 pen. asphalt. All specimens were prepared with 2 hammer blows on one face only.

Figure 5. Fatigue life as a function of sulfur content for a sand-asphalt-sulfur mix. Test temperature 50°F (10°C). Test frequency 60 Hz. Materials medium-coarse sandt and 150/180 pen. asphalt. Asphalt content 6% wt (15),...

Deme, I. J., "Basic Properties of Sand-Asphalt-Sulfur Mixes", International Road Federation World Meeting, 7th, Munich, October, 1973. 

To prevent sulfurization mix the alum separately in a small amount of hot water. Add this solution last with rapid stirring. 

D, direct-substituted sulfur mixes E, mixes using sulfur-asphalt emulsion... 

There are three formulations of sulfur used predominantly today. The first is finely ground sulfur mixed with 1 to 5 percent talc or clay to assist in the dusting effectiveness. The sulfur in this form may be used as a carrier for additional pesticides. The second form is colloidal sulfur that is so fine that it must be formulated as a paste to enable it to be mixed with water. The third form is wettable sulfur. In this formulation the sulfur is finely ground with a wetting agent so that it will mix readily with water for spraying. 

Over 80 percent of the world s production of sulfur is mined in Louisiana and Texas by a very clever method, the Frasch process. The sulfur, mixed with limestone, occurs at depths of about one thousand feet, under strata of sand, clay, and rock. A boring is made to the deposit, and four concentric pipes are sunk (Fig. 17-3). Superheated water (155°) under pressure is pumped down the two outer pipes. This melts the sulfur, which collects in a pool around the open end. Air is forced down the innermost pipe, and a bubbly froth of air, sulfur, and water rises through the space between the innermost pipe and the next one. This mixture is allowed to flow into a very large wooden vat, where the sulfur hardens as a product 99.5% pure. 

The early history of pyrotechnics and the early history of black powder are the same narrative. Incendiary compositions containing saltpeter, and generally sulfur, mixed with combustible materials were used both for amusement and for purposes of w ar. They developed on the one hand into black powder, first used in... 

Sulfur is one of the oldest pesticides known. It has been used for centuries to control both plant pathogens and pests like insects and mites on contact. Sulfur is mined from natural deposits as a yellow solid that is almost insoluble in water. Wettable sulfur is finely ground sulfur mixed with a wetting agent to help it go into solution. Sulfur is also formulated as a... 

So iron and sulfur mixed do not make a compound. They form only a mixture, with individual iron and sulfur atoms merely lying side by side. 

Liquid sulfur mixed with air forms an emulsion that is less dense than water and therefore rises to the surface as it is forced up the middle pipe. Sulfur produced in this manner, which amounts to about 10 million tons per year, has a purity of about 99.5 percent. 

A sharp increase in price and decrease in availability of sulfur reduced the experimental effort temporarily, but laboratory work based on the above findings continued. Pourable paving mixes were developed containing one-sized sands which could be cast in place without rolling, much as portland cement concrete is handled. Based on satisfactory laboratory findings, a test road was constructed in Richmond, British Columbia in 1970, where a sand—asphalt—sulfur mix was cast between forms (5). The success of this trial, coupled with a decrease in the price of sulfur and the forecast for a long-term world sulfur surplus, led us to initiate an extensive research and development program to exploit sand-asphalt-sulfur mixes as road base and surface materials. 

The Function of Sulfur in Sand—Aspbalt-Sulfur Mixes... 

Figure 1. Photomicrograph of a polished sand-asphalt-sulfur mix surface...

The results from full-scale experimental road projects in Canada have confirmed the above findings. When sand-asphalt-sulfur mixes were placed with vibratory screed finishers, increased vibratory energy had no significant effect on the densification of fluid mixes, whereas noticeable increases in density with corresponding increases in vibratory energy were observed with stiffer mix formulations. 

Similar considerations should be remembered when placing graded aggregate-asphalt-sulfur mixes. In this case, however, some vibration is desirable to consolidate all mixes, regardless of consistency, so that the particles are oriented in the most dense configuration. 

In the cement concrete industry the recommended practice is to consolidate low slump mixes by vibration and high slump mixes with hand tools. For example, ASTM Method C 192 (6) specifies consolidating test specimens by vibration if the slump is less than 1 in. Relationships between workability and ease of placing sand-asphalt-sulfur mixes are being evaluated on various field projects to assess the workability requirements for mix placement with various types of equipment. 

Sand-asphalt-sulfur mixes are not subject to particle segregation because of uniform size distribution. These mixes may be transported and handled readily. Sands are, therefore, the best materials for use in paving mixes, considering their low cost in many areas, their ample availability, and their potential for developing high strength in sand-asphalt-sulfur mixes. 

The sand-asphalt-sulfur mix stability increased to a peak value with increasing sulfur content for all asphalt levels. 

Sand-asphalt-sulfur mix stabilities were adequate even with excessively high asphalt contents, e.g., 10% asphalt. 

In conventional asphalt concrete mixes, for which stability is a foremost consideration, the design asphalt content is generally close to the optimum asphalt content for fatigue life. In aggregate-asphalt-sulfur mixes the significant mix properties should be considered independently... 

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