Abstract: A method is shown for raising the pH of a cyanide leach solution of the type used in a heap leaching mining operation. Lime slurry is mixed with a side stream of barren cyanide solution in a reactor vessel in order to remove carbonate hardness, to regenerate the hydroxide alkalinity and to raise the pH of the resulting recausticized leach solution. A portion of the calcium carbonate precipitate formed in the reactor vessel is retained in order to encourage further crystal growth. Overflow from the reactor vessel passes through one or more cyclone separation stages in order to remove particulate solids. A cyclone overflow stream is directed back to the process to upwardly adjust the pH of the bulk of the barren cyanide solution. A cyclone underflow stream is directed back to the reactor vessel to provide seed crystal nuclei for precipitate growth.

Abstract: A method is shown for raising the pH of a cyanide leach solution of the type used in a heap leaching mining operation. Lime slurry is mixed with a side stream of barren cyanide solution in a reactor vessel in order to remove carbonate hardness, to regenerate the hydroxide alkalinity and to raise the pH of the resulting recausticized leach solution. A portion of the calcium carbonate precipitate formed in the reactor vessel is retained in order to encourage further crystal growth. Overflow from the reactor vessel passes through one or more cyclone separation stages in order to remove particulate solids. A cyclone overflow stream is directed back to the process to upwardly adjust the pH of the bulk of the barren cyanide solution. A cyclone underflow stream is directed back to the reactor vessel to provide seed crystal nuclei for precipitate growth.

Abstract: An asphalt roofing composition is provided in the form of a roll or a shingle in which a hot mixture of an asphaltic base and filler is applied to a substrate form, wherein the composition also comprises an amount of Ca(OH)2 (HL) in order to impart strength and durability to the composition. The composition contains HL between about 1-10%, and preferably between about 3-5%, of the total composition by weight. The filler can be fly ash, CaCO3, MgCO2.CaCO3, MgCO3, or other suitable materials known in the art. In a typical embodiment of the invention, the HL is added directly to the asphaltic base of the composition either with the filler, or with filler added after mixing the asphalt and HL.