Process for producing a high concentration coal-water slurry

A process for continuously producing by high coal concentration wet grinding, a coal-water slurry having the desired uniform properties of a viscosity of 2,000 cp or less, a pH of 7 or more, and a coal particle concentration of at least 60% by weight with about 70 to 90% by weight of the coal particles sized so as to pass through a 200 mesh opening, wherein said process comprises the following steps:

• a. selecting and setting the desired quantity of coal-water slurry to be produced into a relay for the quantity of coal fed;
• b. feeding a quantity of coal into a wet-ball mill by means of a coal feeder, wherein the actual amount of coal fed is determined by a detector which generates electrical signals that are transferred to the relays for the quantity of water fed, quantity of coal fed, for the quantity of surfactant added an for the quantity of pH adjustor added;
• c. determining the moisture of the raw coal fed by a detector in the coal feeder which generates electronic signals that are transferred to he relay for the quantity of surfactant added, the relay for the quantity of coal fed, the relay for the quantity of pH adjustor added and to the relay for the quantity of water fed;
• d. Feeding a quantity of water into the wet-ball mill, where the quantity of water fed is determined by a detector at the inlet of the wet-ball mill which generates an electronic signal that is transferred to the relay for the quantity of water fed;
• e. Feeding a quantity of pH adjustor into the wet-ball mill, where the quantity of pH adjustor fed is determined by a detector at the inlet of wet-ball mill which generates electronic signals that are transferred to the relay for the quantity of water fed and to the relay for the quantity of the pH adjustor added;
• f. feeding a quantity of surfactant into the wet-ball mill, where the quantity of surfactant is determined by a detector at the inlet of the wet-ball mill which generates electronic signals that are transferred to the relay for the quantity of water fed and to the relay for the quantity of surfactant added;
• g. grinding and mixing the coal with the water, surfactant and pH adjustor, under conditions of high coal concentration and determining the slurry viscosity inside the wet-ball mill by a detector which generates electronic signals that are transferred to the relay for the quantity of coal fed, to the relay for the quantity of water fed, and to the relay for the quantity of surfactant added;
• h. discharging the coal-water slurry inside the wet-ball mill into a slurry tank and determining the pH of the slurry in the slurry tank by a detector which generates an electronic signal that is transferred to a relay for the quantity of pH adjustor added;
• i. transferring the slurry from the slurry tank to a coarse particle separator and determining the slurry concentration by a detector which generates an electric signal that is transferred to the relays for the quantity of coal fed, for the quantity of water fed, and for the quantity of surfactant added;
• and determining the flow input into the coarse particle separator by a detector for the slurry flow quantity which generates an electronic signal that is transferred to a relay for the slurry particle size, and determining the slurry density of the input slurry by a detector which generates an electronic signal that is transferred to the relay for the slurry particle size;
• j. separating the coarse particles from the slurry in the coarse particle separator and returning to the wet-ball mill the coarse particles, and passing the remaining slurry of fine particles through the coarse particle separator into a product tank and determining the flow output and density of the output slurry by two independent detectors, which generate electronic signals that are sent to the relay for slurry particle size wherein the particle size is computed and electronic signals are generated that are transferred to the relay for the quantity of coal fed, to the relay for the quantity of water fe and to the relay for the quantity of surfactant added;
• and
• k. storing the remaining slurry of fine particle size in the product tank.

An apparatus for continuously producing by high coal concentration wet grinding, a coal-water slurry having a viscosity of 2,000 cp or less, a pH of 7 or more, and a coal particle concentration of at least 60% by weight with about 70 to 90% by weight of the coal particles sized so as to pass through a 200 mesh opening;

• wherein said apparatus consists essentially of:
• a. means for wet grinding raw coal under conditions of high coal concentration to produce a coal-water slurry with a broad coal particle size distribution;
• b. means for detecting slurry viscosity, pH, coal particle concentration, and particle size distribution which generate electrical signals that are transferred to relays;
• c. means for detecting the quantity of coal fed, the moisture of coal fed, the quantity of water fed, the quantity of surfactant added and the quantity of pH adjustor added which generates electrical signals that are transferred to relays;
• d. relay means which received electrical signals from the detectors, compare the information received through these electrical signals with the selected quantity of coal-water slurry, and compute the modified quantities of coal, water, surfactant and pH modifies needed to fulfill the desired properties of the coal-water slurry which are then transferred by electrical signals to adjustors;
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• e. adjustor means which received electrical signals from the relay means, and adjust the amount of coal, water, surfactant and pH modifiers added to the wet grinding means as indicated by the electronic signals.