Abstract: A method produces calcium fulvate from naturally-occurring humus material, such as leonardite, or humic shales. The humus material containing solid fulvic acid and solid humic acid is mixed with water and sodium hydroxide for a first selected period of time to form a solution having a pH of approximately 10.0 thereby solubilizing the fulvic acid and the humic acid. The pH of the solution is reduced to approximately 4.5 and is maintained at the approximately pH 4.5 for second selected period of time thereby precipitating the humic acid as a solid while the fulvic acid remains in solution. The fulvic acid solution is separated from the solid humic acid. The pH of the fulvic acid solution is increased to approximately 13 with calcium hydroxide thereby precipitating the solubilized fulvic acid as calcium fulvate.

Abstract: A method produces magnesium fulvate from naturally-occurring humus material, such as leonardite, or humic shales. The humus material containing solid fulvic acid and solid humic acid is mixed with water and sodium hydroxide for a first selected period of time to form a solution having a pH of approximately 10.0 thereby solubilizing the fulvic acid and the humic acid. The pH of the solution is reduced to approximately 4.5 and is maintained at the approximately pH 4.5 for second selected period of time thereby precipitating the humic acid as a solid while the fulvic acid remains in solution. The fulvic acid solution is separated from the solid humic acid. The pH of the fulvic acid solution is increased to approximately 13 with magnesium hydroxide thereby precipitating the solubilized fulvic acid as magnesium fulvate.

Abstract: A method to detoxify municipal sewage sludge containing heavy metals comprises the steps of mixing sewage sludge, at least one catalytic oxidant such as a ferric salt, at least one regenerative oxidant and an acid to form a reacting slurry having a solids fraction and a liquid fraction and, after a suitable retention time, separating the solids fraction from the liquid fraction. The reacting slurry is maintained during its retention time at a pH range between approximately 1.0 to 2.0 and at an oxidation reduction potential of, at least, +400 milivolts. The heavy metals originally absorbed into the solids fraction of the sewage sludge solubilize into the liquid fraction of the reacting slurry. Thereafter, the reacting slurry is discharged into a conventional solids/liquid separating device so that the metal-laden liquid fraction becomes separated from the solids fraction which is now substantially bar ren of heavy metals.

Abstract: A process and apparatus for the recovery of metals such as silver from phosphate flue dust. The process includes the steps of blending chloride salt and the flue dust to produce a blended material, roasting the blended material in an oxygen bearing atmosphere to oxidize carbon in the blended material producing a gas and to react chloride salt with the metal in the blended material producing a water soluble metallic salt, dissolving the metallic salt in water to produce a solution, filtering the solution to remove solids, and precipitating metals from the filtered solution with the precipitate ready for conventional smelting. The preferred embodiment of the apparatus includes a flue dust hopper and mill and a salt hopper and mill for feeding the dust and salt to a radiant tube dryer and a radiant tube asher for blending and roasting the materials, and a spray chamber at the outlet of the asher for separating solids and gases, where certain of the solids go into solution.

Abstract: An improved process for treating aerobic or anaerobic sewage sludge comprises a two-stage treatment with sulfur dioxides. In the first stage, between 25 and 40 pounds of sulfur dioxide per ton of dry sludge solids as reacted to optimize solids separation while substantially reducing coliform counts to acceptable environmental protection limits. Solids are separated and water discharged. Recovered solids are then treated with between 300-500 pounds of sulfur dioxide per dry solids ton to solubilize heavy, toxic and noble metals which may be recovered from the liquor. Separated sludge solids form a desirable and hazardous metal-free fertilizer.

Abstract: A method of recovering metallic tellurium from a residue dust containing a major amount of lead oxide, a minor amount of tellurium oxide, and a minor amount of iron oxide which comprises the steps of introducing the residue into a leach tank containing water, sulphuric acid and ferric sulphate, the sulphuric acid being present in the leach tank in an amount equal to about 5% to 10% by weight in excess of that stoichiometrically required to react with the lead and tellurium, the ferric sulphate being added as an oxidizing agent, reacting the residue with the sulphuric acid and ferric sulphate to produce lead sulphate and a tellurium solution, removing the lead sulphate and tellurium solution from the leach tank and separating the lead sulphate from the tellurium solution, adding the separated tellurium solution to a tumbler containing particles of metallic iron, agitating the tumbler so that the tellurium solution reacts with the iron to produce ferrous sulphate and metallic tellurium, withdrawing the mixture