Sulfur spray coatings

Air-atmosphere furnaces, 22 290-291 Air atomization, in spray coating, 7 70-72 Air-atomizing sulfur burners, 23 659-660 Airbags, nylon, 19 766 Air-based balanced vinyl chloride process, 25 637, 640, 641, 645 Air-based ethylene oxidation, 20 643-646 Air bioremediation... 

Sulfur Coatings (1J>, 18). Molten sulfur, often mixed with fibers or modifiers can be used to spray coatings on unbonded block or brick buildings, linings for ponds, portland cement concrete, and other applications where a durable coating is required or useful. 

Dale, J. M., Utilizing Sulfur-Based Spray Coatings, Min. Eng. (October... 

Leaves covered with a white powdery coating. Cause Powdery mildew. Leaves may also be twisted or stunted and a powdery coating may cover fruit. Rainy weather does not cause this fungal disease to spread. It is most common in weather patterns featuring cool nights changing to warm days. For control, apply sulfur or lime-sulfur spray. Northstar sour cherry is resistant to powdery mildew. 

Leaves with a white powdery coating on. ike surfaces. Cause Powdery mildew, jne-cred leaves eventually become distorted, un r w a. and fall. Dark patches appear on 3BK5. TMs fungal disease weakens vines, dimin-ines > eld. and makes plants more suscepti-"m winter injury. More common in the t spreads fastest when days are dry and am and nights are cool. For susceptible nar ings. apply sulfur spray in the spring. 

Fruit covered with a powdery w hite coating. Cause Powdery mildew. This fungal disease, most common on red raspberries, makes fruit inedible and may weaken or kill whole canes. Pruning out old canes to provide good air circulation aids control. To prevent the disease, apply sulfur dusts. To control e.xisting infection, apply lime-sulfur spray. Resistant cultivars... 

The results of this study have shown that the physical appearance of sulfur textures in spray coating can be quite variable and that this variation can be correlated with the performance of the coating in controlling the release of nitrogen from a soluble fertilizer. These examinations also... 

Figure 1. Flowsheet of process for coating urea with sulfur and a wax sealant using either pneumatic or hydraulic sulfur-spraying system...

The sulfur-coating drum is about 4 ft in diameter and 6 ft long. The internals of the drum and the associated sulfur piping are completely different depending on whether the sulfur is atomized pneumatically or hydraulically. A schematic of sulfur-coating drum operation with the two types of sulfur spraying is shown in Figure 2. 

USING PNEUMATIC SULFUR SPRAYING USING HYDRAULIC SULFUR SPRAYING Figure 2. Sulfur-coating drum operation... 

The process and the related variables depend on whether the plant is producing sulfur-coated urea with or without a sealant and whether the sulfur is being applied with the pneumatic or hydraulic sulfur-spraying system. 

Pneumatic Sulfur-Spraying System. Sulfur-Coated Urea with Sealant. Figure 3 is a flow diagram of the pneumatic sulfur-spraying system. This system provides better atomization than the hydraulic system, which is discussed later. With the pneumatic system less sulfur is required, producing a higher analysis sulfur-coated urea fertilizer. 

Liquid sulfur temperature. As previously mentioned, the best temperature for sulfur spraying is approximately 310 °F. Tests have shown that as the temperature decreases, the effectiveness of the coating is reduced. Temperatures up to 317°F are acceptable but above 318°F, the sulfur viscosity is so great that good sulfur atomization is virtually impossible. 

Figure 8. Effects of urea temperature in sulfur-coating drum on dissolution of sulfur-coated urea with no seal coating using the pneumatic sulfur-spraying process...

A sulfur-based coating material was developed by Southwest Research Institute to seal and support mine walls. The material was developed under a research contract with the U.S. Department of Interior, Bureau of Mines, for sulfur coatings for mine support (I). As part of the contract they also designed and furnished the Bureau with a portable spray unit for applying the material. 

A sulfur spray formulation containing sulfur, talc, Fiberglas, and dicyclopentadiene was successfully used to construct a block building. The dry-stacked cinder blocks were surface-bonded for structural stability by spraying with a thin coating of the molten formulation. The same formulation also formed an impervious lining on a dirt-formed pond. 

One test developed by Vieille Montagne using 10 ppm SO2 and a daily wash has considerable promise for comparing like products—it has been of use in the evaluation of zinc-aluminum thermally sprayed coatings (Leclerq and Sempels, 1975). Sulfur dioxide tests can sometimes be of value in assessing blistering of paint adjacent to a scratch (Fig. 1.18). 

Blockhuys and co-workers [242] analysed spray-coated thin films of E-poly[(3-methoxy-2,5-thiophenediyl-l",2"-ethenediyl) (4"-methoxy-2",5"-thiophenediyl-l",2"-ethyenediyl)] conducting polymer by grazing emission X-ray fluorescence spectrometry. Measurement of the S/Cl ratio in this sulfur-containing polymer with one terminal chlorine allowed determination of the chain length and, hence, the molecular weight. 

The aliphatic thioethers (polysulfides) are unique among condensation polymers in being produced in an emulsion polymerization. The rank jr (Table 17.2, II.C) has an influence on the number of sulfur atoms in each polymer linkage. The tacky or liquid polymers are cast or applied as pastes in the case of sealants. The sulfur analog of poly(phenylene oxide) is poly(phenylene sulfide) (Table 17.2, II.C), which can be made by a condensation reaction between p-dichlorobenzene and sodium sulfide. The highly crystalline polymer is solvent resistant and has a low coefficient of friction. It can be injection molded at about 300°C and can also be used as a powder spray coating. 

The reproducibility of test results between labs using the neutral salt spray tests has not been consistent, but the repeatability, within one lab, is better, and the test has value in comparing variations in coating systems. Correlation of hours of exposure in the salt spray test to actual performance of the plated part in service, even in marine atmospheres, is not consistent and usually avoided. A classic example is that cadmium deposits outlast zinc deposits on steel in salt spray tests and clean marine atmospheres, yet zinc outlasts cadmium when exposed to real, industrial atmospheres, because of the presence of sulfur-bearing corrodents in industrial environments. An important variable in salt spray testing is the position of the surface to be tested. Whereas the surface of test panels is specified to be 15—30° from the vertical (40), when salt spray testing chromated zinc-plated specimens, this range has appeared excessive (41). 

Thin Layer Chromatography Procedures. Silica gel G (Suppelco, Redi-coat, 5 X 20 cm X 0.25 mm) plates were activated by heating in an oven for 1 hour at 110°C. Toxic products were spotted onto duplicate plates at concentrations corresponding to their previously determined LD99 levels. The plates were developed to 14 cm with chloroform, methanol and (6N) ammonium hydroxide (90 9.5 0.5) or chloroform, methanol, and water (60 35 8). Plates were developed and visualized by spraying with 50% aqueous sulfuric acid and charring. Undeveloped plates were scraped, the silica gel fines removed and the extracts concentrated to a residue under a nitrogen gas stream. 

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