A. General: Supply 6,600 cubic feet of anthracite filter media. B. Quality: 1. The anthracite shall be composed of hard durable grains, and shall be processed from anthracite coal. The anthracite shall be free from any significant amounts of iron sulfides, clay, shale, dust, dirt, or other foreign matter. 2. The solubility of the filter anthracite in a 1:1 mixture of concentrated hydrochloric acid (approximately 37 percent) shall be less than 5 percent. The solubility of the filter anthracite shall be less than 5 percent by weight in 1 percent hot (190 degrees Fahrenheit) sodium hydroxide solution. 3. The filter anthracite shall have a hardness of not less than 2.7 on the MOH scale. 4. Average apparent specific gravity shall be determined by the procedure set forth in ASTM C 128, which provides for soaking the sample in water for 24 hours. The filter anthracite shall have a specific gravity of not less than 1.40, nor more than 1.70. 5. The filter anthracite shall not have more than 1 percent by weight flat and sliver-like (combined) particles. Flat and sliver-like shall be defined as a ratio of the longest axis to the shortest axis of the circumscribing rectangular prism 6. The filter anthracite shall have an ash (dry) content of less than or equal to 15 percent as determined by ASTM D 3174. 7. The filter anthracite shall have a volatiles (dry ash free) content of less than or equal to 7 percent as determined by ASTM D 3175. 8. The filter anthracite shall have a Hardgrove Grindability index of less than or equal to 38 as determined by ASTM D 409. C. Size: 1. The anthracite shall meet the following requirements: a. Effective (10 percent) size (mm) - 1.0 to 1.1 mm. b. 60 percent size (mm) - 1.05 to 1.40 mm.
