Waste treatment method for metal hydroxide electroplating sludges
First Claim
1. A waste treatment method for metal hydroxide sludges generated from electroplating waste water treatment, said method comprising the steps of:
- dewatering said sludge;
heating said metal hydroxide sludge, in an oxidizing environment, to a temperature sufficient to cause substantially all said metal hydroxides in said sludge to convert to metal oxides, thereby forming a metal oxide sludge;
mixing said metal hydroxide sludge, or said metal oxide sludge formed therefrom, with predetermined quantities of silica and soda;
heating said mixture of metal oxide sludge, silica and soda, to a temperature sufficient to cause fusion thereof to form a slag-like composition; and
cooling said fused slag-like composition to ambient temperature to form a solidified mass that is predominantly crystalline in structure and has a substantial quantity of said metal oxides in solid solution, either in a precipitate phase or in a silicate matrix.
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Abstract
A waste treatment method for metal hydroxide electroplating sludges. Metal hydroxide sludges from the treatment of electroplating waste waters are rendered environmentally safe. The sludges are first dewatered and heated to a temperature sufficient to cause the metal hydroxides to convert to metal oxides. Predetermined quantities of silica and soda, or sources thereof, are mixed with the metal oxides. The mixture is further heated to a temperature sufficient to cause fusion of the mixture and form a slag-like composition having the metal oxides in chemical solution. The slag-like composition is then cooled to ambient temperature. The structure of the cooled slag-like composition is predominantly crystalline, having the metal oxides in solid solution in either a precipitate phase or a silicate matrix. The slag-like composition is resistant to corrosion even in an acidic environment.
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Citations
17 Claims
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1. A waste treatment method for metal hydroxide sludges generated from electroplating waste water treatment, said method comprising the steps of:
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dewatering said sludge; heating said metal hydroxide sludge, in an oxidizing environment, to a temperature sufficient to cause substantially all said metal hydroxides in said sludge to convert to metal oxides, thereby forming a metal oxide sludge; mixing said metal hydroxide sludge, or said metal oxide sludge formed therefrom, with predetermined quantities of silica and soda; heating said mixture of metal oxide sludge, silica and soda, to a temperature sufficient to cause fusion thereof to form a slag-like composition; and cooling said fused slag-like composition to ambient temperature to form a solidified mass that is predominantly crystalline in structure and has a substantial quantity of said metal oxides in solid solution, either in a precipitate phase or in a silicate matrix. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification