The Carborundum Company

Hari N Murty

Granular activated carbon is manufactured from sub-bituminous coal by crushing and screening the as received coal containing about 10 to about 25% moisture by weight to produce 8/30 mesh granules, treating the granules with a dilute aqueous solution of inorganic acid at a concentration from about 1 to about 25% by weight to reduce the volatile content and thereby increase the fixed carbon content, the particular concentration being selected to provide the desired activity and porosity of the activated carbon, comprising: mixing the granules with the acid, washing off the acid, and drying the granules at least partially to a moisture content below about 25% by weight. The granules are mixed with from 0 to about 15% by weight of coal tar pitch. The so treated granules are ground to form fine powder of not less than about 60% by weight -325 mesh, preferably more than about 65% by weight -325 mesh, which is compressed into shapes, such as pellets or thin corrugated sheets under high pressure, and then granulated to reform 6/20 mesh granules. These reformed granules are then directly activated, without prior charring and devolatilization, by directly heating to and at a temperature higher than the devolatilizing temperature in an atmosphere containing a gaseous activating agent.

Granular activated carbon manufacture from sub-bituminous coal treated

Granular activated carbon is manufactured from briquettes of about 1'.times.2', formed from brown coal, from which iron material has been extracted and which has a moisture content of about 15% by weight, by crushing and screening the pretreated coal briquettes to produce 8/30 mesh granules, treating the granules with a dilute aqueous solution of inorganic acid (H.sub.2 SO.sub.4, H.sub.3 PO.sub.4 or HCl) at a concentration of about 1 to about 10% by weight to reduce the volatile content and thereby increase the fixed carbon content comprising: mixing the granules with the acid, washing off the acid, and drying the granules at least partially to a moisture content below about 25% by weight. In one case the washed granules are dried partially to a moisture content of about 10 to about 25% by weight without the addition of a carbonaceous binder such as coal tar pitch. In the other case the granules are dried thoroughly and mixed with about 5 to about 15% by weight of coal tar pitch. The so treated granules are ground to form fine powder of more than about 65% by weight -325 mesh, more preferably 75 to 85% by weight -325 mesh, which is compressed into shapes such as pellets of 0.5' diameter and 0.5' long under a pressure of 40,000 to 80,000 psi, and then granulated to obtain 6/20 mesh granules. These reformed granules are devolatilized, without charring, by directly heating to and at a temperature higher than the charring temperature in an oxygen-free atmosphere, and then activated by heating to and at a temperature higher than the devolatilizing temperature in an atmosphere containing a gaseous activating agent. The overall yield of granular activated carbon is not less than about 22% by weight, dry basis, and the activated granules have a surface area of not less than about 900 m.sup.2 /gram, an Iodine number of not less than about 900, an ash content of not more than about 7% by weight, an abrasion number of not less than about 70, an apparent density of not less than about 0.46 gram/cc, and a Molasses number of not less than about 200; which properties make them suitable for use in water and waste water treatment and in other applications.

Granular activated carbon manufacture from brown coal treated with

Granular activated carbon is manufactured from briquettes of about 1.times. 2' mesh formed from brown coal from which iron material has been extracted and which has a moisture content of about 15% by weight, by crushing and screening the pre-treated coal briquettes to produce 8/30 mesh granules, which are treated by mixing with about 5% by weight of concentrated inorganic acid (H.sub.2 SO.sub.4, H.sub.3 PO.sub.4, or HCl), without the addition of a carbonaceous binder such as coal tar pitch. The so treated granules are ground to form fine powder of more than about 65% by weight -325 mesh powder, more preferably 75 to 85% by weight -325 mesh, which powder has a moisture (including acid) content of about 21% by weight, as a temporary binder, and which powder is compressed into shapes such as pellets of 0.5' diameter and 0.5' long under a pressure of 40,000 to 80,000 psi, and then granulated to obtain 6/20 mesh granules. These granules are devolatilized, without charring, by directly heating to and at a temperature higher than the charring temperature in an oxygen-free atmosphere, and then activated by heating to and at a temperature higher than the devolatilizing temperature in an atmosphere containing a gaseous activating agent. The overall yield of granular activated carbon is not less than about 22% by weight, dry basis, and the activated granules have a surface area of not less than about 900 m.sup.2 /gram, an iodine number of not less than about 900, an ash content of not more than about 6% by weight, an abrasion number of not less than about 70, an apparent density of not less than about 0.48 gram/cc, and a Molasses number of not less than about 200; which properties make them suitable for use in water and waste water treatment and in other applications.

Granular activated carbon is manufactured from sub-bituminous coal by crushing and screening the as received coal containing about 10 to about 25% moisture by weight to produce 8/30 mesh granules, treating the granules with a dilute aqueous solution of inorganic acid at a concentration from about 1 to about 25% by weight to reduce the volatile content and thereby increase the fixed carbon content, the particular concentration being selected to provide the desired activity and porosity of the activated carbon, comprising: mixing the granules with the acid, washing off the acid, and drying the granules at least partially to a moisture content below about 25% by weight. The granules are mixed with from 0 to about 15% by weight of coal tar pitch. The so treated granules are ground to form fine powder of not less than about 60% by weight -325 mesh, preferably more than about 65% by weight -325 mesh, which is compressed into shapes, such as pellets or thin corrugated sheets under high pressure, and then granulated to reform 6/20 mesh granules. These reformed granules are devolatilized, without prior charring, by directly heating to and at a temperature higher than the charring temperature in an oxygen-free atmosphere, and then activated by heating to and at a temperature higher than the devolatilizing temperature in an atmosphere containing a gaseous activating agent.

Granular activated carbon is manufactured from low rank agglomerating but not good coking bituminous coal by crushing and screening the as received coal to produce 8/30 mesh granules, which are treated with a dilute aqueous solution of inorganic acid to prevent fusion of the granules during subsequent devolatilization comprising: mixing the granules with the acid (H.sub.2 SO.sub.4, H.sub.3 PO.sub.4, HCl or mixtures thereof) at a concentration of about 1% to about 15% by weight, washing off the acid, drying the granules thoroughly and thereafter mixing the granules with about 5 to about 15% by weight of a carbonaceous binder such as coal tar pitch. The so treated granules are ground to at least about 65% by weight -325 mesh powder, which is compressed into shapes such as pellets of 0.5 inch diameter and 0.5 inch long under a pressure of 40,000 to 80,000 psi, and then granulated to obtain 6/20 mesh granules. These granules are first charred by heating to 250.degree. C at 150.degree. C/hour in an atmosphere of air and nitrogen and by maintaining the temperature for 4 hours, next devolatilized by heating to 450.degree. C at 300.degree. C/hour in an atmosphere of N.sub.2 and the volatiles and by maintaining the temperature for 1 hour, and then activated by heating to 800.degree. to 900.degree. C in an atmosphere of N.sub.2 and steam and by maintaining the temperature for 4 to 5 hours. The activated granules have a surface area of 1050 to 1090 m.sup.2 /gram, an Iodine number of 900 to 1100, an ash content of 6 to 9%, an abrasion number 75 to 80, and an apparent density of 0.51 to 0.53 gram/cc, which properties make them suitable for use in water and waste water treatment and in other applications.

Granular activated carbon manufacture from low rank agglomerating but

Granular activated carbon is manufactured from sub-bituminous coal by crushing and screening the as received coal containing 17% moisture by weight to produce 8/30 mesh granules which are treated by mixing with about 5% by weight of concentrated inorganic acid (H.sub.2 SO.sub.4, H.sub.3 PO.sub.4 or HCl), without the addition of a carbonaceous binder. The so treated granules are ground to more than 65% by weight -325 mesh powder, preferably 75 to 85% by weight -325 mesh, which powder has a moisture (including acid) content of about 21% by weight, as a temporary binder, and which powder is compressed into pellets of 0.5 inch diameter and 0.5 inch long under a pressure of 40,000 to 80,000 psi, and then granulated to obtain 6/20 mesh granules. These granules are devolatilized by heating to 450.degree. C at 300.degree. C/hour in an atmosphere of N.sub.2 and the volatiles and by maintaining the temperature for 1 hour, and then activated by heating to 800.degree. to 900.degree. C in an atmosphere of N.sub.2 and steam and by maintaining the temperature for 4 to 5 hours. The overall yield of granular activated carbon is 25 to 35% by weight of the dry coal, and the activated granules have a surface area of 900 to 1050 m.sup.2 /gram, an iodine number of 900 to 1100, an ash content of 10 to 12%, an abrasion number of 80, and an apparent density of 0.48 to 0.50 gram/cc, which properties make them suitable for use in waste water treatment and other applications.

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Grand Island, NY, United States of America

Hari N Murty