Washability

Coal washing is a process by which mineral matter is removed from coal by the use of any one of several washing processes to leave the coal as near mineral-free 

Extrinsic mineral matter, which is purely adventitious, is derived from the roof and floor of the coal seam and from any noncoal or inorganic material that may be associated with the seam itself. It consists generally of pieces of stone, clay, and shale together with infiltrated inorganic salts that have become deposited in the natural fissures in the coal seam (e.g., pyrite, ankeritic material). Such material can be reduced very much in amount by suitable methods of coal cleaning and, indeed, may be separated from the coal completely, provided that it can be broken apart from coal particles. 

Determination of the washability characteristics of coal by the float and sink (float-sink) method can be applied to coal of any particle size provided suitably large vessels to hold the larger lumps are available. Air-dried coal, not dry coal, should be used since the separation depends partly on the difference in specific gravity of the clean coal and dirt particles, and the specific gravity, in turn, is dependent on the moisture content of the coal. If the coal is dried before the test is carried out, the conditions will then differ from those in commercial washers, and the results will be at variance with those obtained in practice. 

If bromoform is used, it is best to wash the fractions after filtration with a little methyl alcohol to dissolve the bromoform since the high boiling point of bromoform [151°C (304°F)] makes it difficult to remove completely by air drying. Furthermore, although it has been recommended that solutions of inorganic salts (e.g., calcium chloride, zinc chloride) in water may be used to replace the more expensive organic solvents, it is almost impossible to remove these salts from 

With decreasing particle size, the practical feasibility of gravity separation diminishes because the efficiency of separation is reduced. Particularly in low-volatile coals, a substantial proportion of the coal may be lost in these fines if other means are not applied for separating them from the slime (clay) and recovering them. Froth flotation is one technique that is used for this purpose. 

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This paper describes the result obtained in a study of AFCEN (French Society for Design and Construction Rules for Nuclear Island Components) in order to characterize dye penetrant product family, based on experimental test methods of french standards NFA 09.520 and NFA 09.521. In particular, sensitivity tests have been carried out on artificial defects, and correlated with tests on real defects. Some tests on penetrant washability have also been performed. The results obtained with these three series of tests show that the choiee of a dye penetrant product family is not without influency on results obtained, and that is not so simple to make the good choice which could, in certain cases, be the less bad compromise. 

The removing penetrant test is performed on sanded and cracked reference block defined in standard NFA 09.520 ( see figure 1, annex 1) and permits the evaluation of the washability of penetrants. 

The membrane is usually made from one of several materials. Woven polyester or cotton, the most commonly used and least expensive material, is adequate for temperatures up to 150°C. Siatered plastic is used where a low cost, washable surface is desired. This material is temperature limited by the polymer material to about 60°C and the flow of some powders may cause a static charge build-up on the membrane that could be hazardous ia some operatioas. Wovea fiberglass fabric or porous ceramic block is used for temperatures up to about 425°C. Siatered stainless steel powder or bonded stainless mesh is used for corrosion resistance, and for temperatures up to 530 to 650°C. Additional information can be found ia the Hterature (38,39). 

The sulfur content of U.S. coals varies widely, ranging from a low of 0.2 percent to as much as 7 percent by weight, on a diy Basis. The estimated remaining U.S. coal reserves of all ranks, by sulfur content, are shown in Fig. 27-1. Extensive data on sulfur and sulfur reduc tion potential, including washability, in U.S. coals are given in Sulfur and Ash Reduction Potential and Selected Chemical and Physical Properties of United States Coal (U.S. Dept, of Energy, DOE/PETC, TR-90/7, 1990 TR-91/1 andTR-91/2, 1991). 

There are three main types of filter viscous, dry and HEPA. Viscous filters are normally a coarse weave of glass, plastic or metal strands coated with oil. As the air passes through the filter, particles impact against the material and are held in the oil. The panels are normally washable and can be re-used after re-oiling. Viscous filters provide good general filtration for air inlet to buildings. 

The action of most filters is mechanical. These are normally scrapped when fully loaded but may, for lower efficiencies, be washable. Another type uses electrostatic charges. 

Some laboratories may even want to consider using wallpaper in a limited area. An appropriate pattern of solid vinyl wall covering, which is both resistant and very washable, can be a cheerful addition when used in the right place. Wood paneling in an office area is another possibility that should not be overlooked. Little extras like these can make a great deal of difference in comfort and morale, usually at a modest cost. 

Melt the stearyl alcohol, white wax, and cholesterol (steam bath). Add the petrolatum and continue heating until a liquid melt is formed. Cool with stirring until congealed. III. Water-washable ointment (hydrophilic ointment, USP) White petrolatum 25% (w/w)... 

Their discoveries—white clothes, cheap soap and sugar, brightly colored washable fabric, clean water, fertilizer, powerful aviation and automotive fuel, safe refrigerants, synthetic textiles, pesticides, and lead-free fuel and food—were enthusiastically embraced by the buying public. Few of us today would want to do without them. 

Chemical bleaching is used to remove colored non-washable soils and stains adhering to fibers and is accomplished by oxidative or reductive decomposition of chromophoric systems. Only oxidative bleaches are used in laundry products to a great extent. 

The key to design of animal facilities is simplicity. All surfaces should be washable and a water source available In each... 

BANDAGE ELASTIC FLESH ROLLED 4.5YDX4"WASHABLE PRESSURE 12S 6510009355822 PG 8.50 ... 

To make the written image darker and more legible at the outset, additional dyes are added to the mixture. Modem coloured inks, and washable inks, contain a soluble synthetic dye as the sole chromophore, ensuring s is large and obviating the requirement for overwriting. 

Polychlorotrifluoroethylene (PCTFE) is ordinarily prepared by emulsion polymerization. A polymer suitable for thermal processing requires coagulation, extensive washing, and postpolymerization workup. Coagulation to provide a filterable and washable solid is a slow, difficult process and removal of surfactant is an important part of it. Complete removal may be extremely difficult depending on the extent of adsorption to the polymer particles. Consequently we set out to develop a suspension polymerization process, which would be surfactant-free and afford an easily isolated product requiring a minimum of postreaction workup. 

Polypropylene is used in sterilisable medical and chemical equipment machine parts, food packs, book coverings, packing meat and cheese, washable wall paper yarn to make socking, etc. 

Airborne particles, bacteria, fungi spores and allergens will be removed by air filtration, which is often cheaper and more effective than electrostatic precipitators and ionizers. A disposable, high-efficiency filter capable of removing at least 95 percent of particles with size down to 0.3 micron will be installed. A washable coarse filter that removes fifty percent of particles larger than 10 microns will be used as a pre-filter to extend the life of the high efficiency filter by at least a third. An inexpensive sensor will be included to indicate when filter replacement is necessary. 

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