Recovery of potential energy and chromium values from leather tannery wastes
AssigneeSystems Consultants, Inc.
InventorH. S. Muralidhara
Life of this patent
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Abstract
A method of recovering chromium values and potential energy from liquid and solid leather tannery wastes comprising pyrolyzing the tannery wastes to produce a burnable fuel product comprising gases and liquids and a substantially solid chromium-containing residue, recovering chromium compounds from the solid residue and using the fuel to supply energy for the system.
Claims13
A method of treating substantially solid tannery waste material containing chromium and organic matter to recover chromium in the +3 valence state and to produce fuel products comprising:
- (a) pyrolyzing said solid tannery waste to produce a fuel product comprising burnable gases and liquids and substantially solid residue containing chromium in a +3 valence state as an organic chromium complex soluble in an about 1 M sulfuric acid solution,
- (b) separating said burnable fuel product from said chromium-containing residue, and
- (c) recovering chromium compounds from said residue by dissolution in an about 1 M sulfuric acid solution
- said pyrolysis comprising subjecting said solid tannery waste in a pyrolysis zone to a temperature between 500.degree. F. and 932.degree. F. in the absence of an amount of gaseous oxygen substantially above about 10%.
A method of treating both liquid and solid tannery waste containing chromium and organic material to recover chromium and to produce burnable fuel products comprising:
- (a) de-watering and substantially drying said liquid tannery waste,
- (b) combining said de-watered and dried liquid tannery waste with said solid tannery waste
- (c) pyrolyzing said combined wastes in a pyrolysis zone at a temperature of from about 500.degree. F. to about 932.degree. F. in the absence of an amount of gaseous oxygen substantially above about 10% to produce a burnable fuel product comprising gases and liquids and a substantially solid residue containing chromium in a +3 valence state as an organic chromium complex soluble in an about 1 M sulfuric acid solution,
- (d) separating said burnable fuel product from said chromium-containing residue,
- (e) recovering chromium from said residue by dissolution in an about 1 M sulfuric acid solution,
- (f) burning a portion of said burnable fuel product to supply heat to said pyrolysis zone, and
- (g) burning a portion of said burnable fuel product in a boiler to produce hot water and/or steam.
In a process for tanning leather with a chromium-containing compound whereby chromium compound containing liquid and solid leather waste materials are produced as by-products, the improvement comprising:
- (a) de-watering and substantially drying said liquid tannery waste,
- (b) combining said de-watered and dried liquid tannery waste with said solid tannery waste,
- (c) pyrolyzing said combined wastes in a pyrolysis zone at a temperature of from about 500.degree. F. to about 932.degree. F. in the absence of an amount of gaseous oxygen substantially above about 10% to produce a burnable fuel product comprising gases and liquids and a substantially solid residue containing chromium in a +3 valence state as an organic chromium complex soluble in an about 1 M sulfuric acid solution,
- (d) separating said burnable fuel product from said chromium-containing residue,
- (e) recovering chromium from said residue by leaching with an about 1 M sulfuric acid solution,
- (f) burning a portion of said burnable fuel product to supply heat to said pyrolysis zone,
- (g) burning a portion of said burnable fuel product in a boiler to produce hot water and/or steam, and
- (h) recycling said recovered chromium to said tanning step.
Dependencies are inferred from the claim text.