Abstract: Small, wet particulate material is effectively dried by adding a hydrophobizing agent to coat the surfaces of the particulates, and then mechanically removing water droplets from the surfaces of the particulates. Once on the surface of the particulates, the hydrophobizing reagent makes the particulates relatively more hydrophobic and increases the water contact angle on the particulates. The moisture content of the particulate material can easily be reduced to levels below 20%, below 10%, and even below 5%. The process can be used to dewater a wide variety of constituents including coal particles, clays, sulfides, phosphorous compounds, minerals, metals, waste sludge, etc. Particularly preferred hydrophobizing reagents include mono unsaturated fatty esters and polysiloxane polymers.

Abstract: Fine particles are dewatered in an energy efficient process in which a non-polar liquid or a mixture of different hydrophobic liquids are used to displace the water from the particle surface. Thermodynamically, this process is spontaneous. The only energy required for this process is to recover the hydrophobic liquid(s) for recycling purposes. The hydrophobic liquids are recovered in gaseous form either by lowering the pressure or by heating, and converted back to liquid form for re-use. The most economical reagents that can be used for this purpose include propane, butane, pentane, and ethane. Carbon dioxide may also be used for the dewatering process described in the present invention. The process of dewatering by displacement is capable of achieving the same or better level of moisture reduction as thermal drying but at substantially lower energy costs.

Abstract: An apparatus for separating impurities from coal, includes a device for removing a predetermined amount of ash-forming substances from the coal and a device for removing a predetermined amount of high specific gravity (e.g., pyrite) from the coal having been processed by the ash-forming substance removing device. The ash-forming substance removing device and the high specific gravity material removing device each possess characteristics that allow them to more efficiently reject different types of mineral impurities from coal.

Abstract: Fine coals are dewatered in an energy efficient process in which a non-polar liquid or a mixture of different hydrophobic liquids are used to displace the water from the coal surface. This process works with higher rank coals that are naturally hydrophobic so that the coal surface from which the water is displaced has a stronger affinity for the hydrophobic liquid than the water. Thermodynamically, this process is spontaneous and, hence, requires no energy. The only energy required for this process is to recover the spent hydrophobic liquid(s) for recycling purposes. The hydrophobic liquids are recovered in gaseous form either by lowering the pressure or by heating, and coverted back to liquid form for re-use. The most economical reagents that can be used for this purpose include propane, butane, pentane, and ethane. Carbon dioxide can also be used for the dewatering process described in the present invention.

Abstract: An apparatus is disclosed for the microbubble flotation separation of very fine and coarse particles, especially coal, and minerals so as to produce high purity and high recovery efficiency. This is accomplished through the use of a flotation column, microbubbles, recycling of the flotation pulp, and countercurrent wash water to gently wash the froth. Also disclosed are unique processes and apparatus for generating microbubbles for flotation in a highly efficient and inexpensive manner using either a porous tube or in-line static generators.

Abstract: Mineral content in processed ore and coal content in coal slurries are determined using a video system. A video image is taken of a sample, the video image is digitized, and gray levels are assigned to points or areas on the video image. The distribution of the gray levels for the image provides an indication of the purity of the minerals in the ore sample. The mean gray level for the image provides an indication of the mineral content of interest in the sample. The video system should be calibrated using ores that normally occur in the process environment and using samples of controlled moisture content. The video system has particular utility in determining phosphate content and calcium ratio in phosphate ores.

Abstract: A method and apparatus are disclosed for the microbubble flotation separation of very fine and coarse particles, especially coal and minerals, so as to produce high purity and high recovery efficiency. This is accomplished through the use of a flotation column, microbubbles, recycling of the flotation pulp, and countercurrent wash water to gently wash the froth. Also disclosed are unique processes and apparatus for generating microbubbles for flotation in a highly efficient and inexpensive manner using either a porous tube or in-line static generators.

Abstract: A process of selectively agglomerating coal in an aqueous environment while leaving the mineral matter dispersed has been developed. This process is autogenous for hydrophobic particles in that neither an agglomerating agent nor an electrolytic coagulant is needed. It is based on the finding that hydrophobic particles are pushed against each other by the surrounding water structure. This process, which is referred to as selective hydrophobic coagulation, is driven by the so-called hydrophobic interaction energy, which is not included in the classical DLVO theory describing the stability of lyophobic suspensions. The relatively small coagula formed by the selective hydrophobic coagulation process can be readily separated from the dispersed mineral matter by several different techniques such as screening, elutriation, sedimentation and froth flotation.

Abstract: A method and apparatus are disclosed for the microbubble flotation separation of very fine particles, especially coal, so as to produce a high purity and large recovery efficiently. This is accomplished through the use of a high aspect ratio flotation column, microbubbles, and a countercurrent use of wash water to gently wash the froth. Also, disclosed are unique processes and apparatus for generating microbubbles for flotation in a high efficient and inexpensive manner using either a porous tube or an in-line static generator.

Abstract: By Ferric Ion Treatment of crushed and/or pulverized coal, the ash content of a coal can be significantly and efficiently reduced. This treatment of coal, preferably in an acidic medium, creates an increase in osmotic pressure inside the pores and crevices of the coal matrix until they open up, allowing the ash-forming mineral matter to be released from the coal. Also, the ferric ions preferentially attack the sessile bonds of the coal molecule and help open up the pores. The liberated mineral matter is then separated from the coal to obtain a clean coal. A flow-through reactor, utilizing working, reference and counter electrodes, and a loosely-packed coal bed through which the electrolyte flows, is particularly effective in facilitating the Ferric Ion Treatment.

Abstract: An improved flotation process for removal of colored titaniferous impurities from kaolin clay uses as collector a hydroxamate compound, or a mixture of compounds, having the formula ##STR1## in which R is an alkyl, aryl, or alkylaryl group having 4-28, and preferably 6-24 carbon atoms, and M represents an alkali metal, an alkaline earth metal or hydrogen. The process does not require the use of activators to make the collector adsorb selectively on the colored impurities.