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US 5,464,596 AGranted
Method for treating waste streams containing zinc
AssigneeMetals Recycling Technologies Corp.
InventorAllan S. Myerson
Life of this patent
Estimating the term…
Abstract
A method for the recovery of zinc products, including zinc oxide and elemental zinc, and optionally iron-carbon feedstocks, from industrial waste streams containing zinc and iron, by treating the waste streams with carbon and an ammonium chloride solution, separating any undissolved components from the solution, displacing undesired metal ions from the solution using zinc metal, treating the solution to remove therefrom zinc compounds, and further treating the zinc compounds and the undissolved components, as necessary, resulting in the zinc products and the optional iron-carbon feedbacks.
Claims50
A continuous method for the recovery of zinc oxide from waste material streams which comprise zinc compounds, comprising the steps of:
- a. roasting said waste material at an elevated temperature and in a reducing atmosphere;
- b. treating said waste material with an ammonium chloride solution at an elevated temperature to form a product solution which comprises dissolved zinc and dissolved zinc oxide whereby any iron oxide in said waste material will not go into solution;
- c. separating said product solution from any undissolved materials present in said product solution including any of said iron oxide;
- d. adding zinc metal and a dispersant to said product solution whereby any lead and cadmium ions contained within said product solution are displaced by said zinc metal and precipitate out of said product solution as lead and cadmium metals and said dispersant is selected from the group consisting of dispersants which will prevent the aggregation of said zinc metal;
- e. separating said product solution from the lead and cadmium metals;
- f. lowering the temperature of said product solution thereby precipitating the zinc component as a mixture of crystallized zinc compounds;
- g. separating said precipitated zinc compounds from said product solution;
- h. washing said zinc compounds solids with a wash water thereby solubilizing certain of said zinc compounds;
- i. separating the remaining zinc compounds solids from said solution;
- and then
- j. drying said remaining zinc compounds solids at a temperature of at least 100.degree. C. whereby said resulting product is zinc oxide of 99% or greater purity.
8 more elements
A continuous method for the recovery of zinc oxide from waste material streams which comprise zinc compounds, comprising the steps of:
- a. treating said waste material a first time with an ammonium chloride solution at an elevated temperature to form a first product solution which comprises dissolved zinc constituents whereby any iron oxide in said waste material will not go into solution;
- b. separating said first product solution from the undissolved waste material compounds present in said first product solution including any of said iron oxide;
- c. roasting said undissolved waste material compounds at an elevated temperature and in a reducing atmosphere;
- d. treating said roasted undissolved waste material compounds a second time with said ammonium chloride solution at an elevated temperature to form a second product solution which comprises dissolved zinc constituents whereby any iron oxide remaining in said roasted undissolved waste material compounds will not go into solution;
- e. separating said second product solution from said roasted undissolved waste materials present in said second product solution including any of said iron oxide;
- f. combining said first and second product solutions to form a combined product solution, maintaining said combined product solution at a temperature of at least 90.degree. C., and adding powdered zinc metal and a dispersant to said combined product solution whereby any lead and cadmium ions contained within said combined product solution are displaced by said zinc metal and precipitate out of said combined product solution as lead and cadmium metals and said dispersant is selected from the group consisting of dispersants which will prevent the aggregation of said zinc metal;
- g. separating said combined product solution from the lead and cadmium metals;
- h. lowering the temperature of said combined product solution thereby precipitating the zinc component as a mixture of crystallized zinc compounds;
- i. separating said precipitated zinc compounds from said combined product solution;
- j. washing said zinc compounds solids with a wash water having a temperature of between about 25.degree. C. and 100.degree. C. thereby solubilizing certain of said zinc compounds;
- k. separating the remaining zinc compound solids from said combined product solution;
- and
- l. drying said remaining zinc compound solids at a temperature of between about 100.degree. C. and 350.degree. C. whereby said resulting product is zinc oxide of 99% or greater purity.
10 more elements
A continuous method for the recovery of products from waste material streams which comprise zinc compounds, comprising the steps of:
- a. treating said waste material with an ammonium chloride solution at an elevated temperature to form a product solution which comprises dissolved zinc and dissolved zinc oxide whereby any iron oxide in said waste material will not go into solution;
- b. adding carbon to said product solution whereby said carbon will not go into solution;
- and
- c. separating said product solution from any undissolved materials present in said product solution including any of said iron oxide and said carbon.
1 more element
A continuous method for the recovery of zinc oxide from waste materials which comprise compounds of zinc, iron, lead and cadmium, comprising the steps of:
- a. roasting said waste material at a temperature of at least 500.degree. C. and in a reducing atmosphere comprising carbon;
- b. treating said waste material with a 23% ammonium chloride solution maintained at a temperature of at least 90.degree. C. to form a product solution which comprises compounds of zinc, lead and cadmium whereby any iron oxide in said waste material will not go into solution;
- c. separating said product solution from the undissolved compounds of iron and any other undissolved materials present in said product solution including any of said iron oxide;
- d. adding powdered zinc metal and a dispersant to said product solution whereby the lead and cadmium ions contained within said product solution and displaced by said zinc metal and precipitate out of said product solution as lead and cadmium metals and said dispersant is selected from the group consisting of dispersants which will prevent the aggregation of said zinc metal;
- e. separating said product solution from the lead and cadmium metals;
- f. lowering the temperature of said product solution in a controlled fashion over a predetermined period of time to a temperature of between about 20.degree. C. and 60.degree. C. thereby precipitating out said compounds of zinc, including diamino zinc dichloride and hydrated zinc oxide;
- g. separating said precipitated zinc compounds from said product solution;
- h. recycling said product solution after said zinc compounds are precipitated therefrom in step d to be employed in step b;
- i. washing said zinc compounds with a wash water at a temperature of between about 25.degree. C. and 100.degree. C. thereby solubilizing the diamino zinc chloride component;
- j. concentrating said wash water after said zinc oxide is separated therefrom by the removal of pure water therefrom, and recycling said wash water to be employed in step i;
- k. separating the remaining zinc compound solids from said product solution;
- and
- l. drying said remaining zinc compound solids for between about 2 minutes and 60 minutes at a temperature of between about 271.degree. C. and 350.degree. C. resulting in zinc oxide of 99% or greater purity.
10 more elements
A continuous method for the recovery of zinc oxide from waste materials which comprise compounds of zinc, iron, lead and cadmium, comprising the steps of:
- a. treating said waste materials a first time with a 23% ammonium chloride solution maintained at a temperature of at least 90.degree. C. to form a first product solution which comprises dissolved compounds of zinc, lead and cadmium whereby any iron oxide in said waste materials will not go into solution;
- b. separating said first product solution from the undissolved compounds of iron and any other undissolved waste materials present in said first product solution including any of said iron oxide;
- c. roasting said undissolved waste materials at a temperature of at least 500.degree. C. and in a reducing atmosphere comprising carbon;
- d. treating said roasted undissolved waste materials a second time with said ammonium chloride solution maintained at a temperature of at least 90.degree. C. to form a second product solution which comprises dissolved compounds of zinc, lead and cadmium whereby any iron oxide remaining in said roasted undissolved waste materials will not go into solution;
- e. separating said second product solution from said roasted undissolved waste materials present in said second product solution including any of said iron oxide;
- f. combining said first and second product solutions to form a combined product solution and adding powdered zinc metal and a dispersant to said combined product solution whereby the lead and cadmium ions contained within said combined product solution are displaced by said zinc metal and precipitate out of said combined product solution as lead and cadmium metals and said dispersant is selected from the group consisting of dispersants which will prevent the aggregation of said zinc metal;
- g. separating said combined product solution from the lead and cadmium metals;
- h. lowering the temperature of said combined product solution in a controlled fashion over a predetermined period of time to a temperature of between about 20.degree. C. and 60.degree. C. thereby precipitating out said compounds of zinc, including diamino zinc dichloride and hydrated zinc oxide;
- i. separating said precipitated zinc compounds from said combined product solution;
- j. recycling said combined product solution after said zinc compounds are precipitated therefrom in step e to be employed in steps a and d;
- k. washing said zinc compounds with a wash water at a temperature of between about 25.degree. C. and 100.degree. C. thereby solubilizing the diamino zinc chloride component;
- l. concentrating said wash water after said zinc oxide is separated therefrom by the removal of pure water therefrom, and recycling said wash water to be employed in step k;
- m. separating the remaining zinc compound solids from said combined product solution;
- and
- n. drying said remaining zinc compound solids for between 2 minutes and 60 minutes at a temperature of between about 271.degree. C. and 350.degree. C. resulting in zinc oxide of 99% or greater purity.
12 more elements
A continuous method for the recovery of products from waste material streams which comprise zinc compounds, comprising the steps of:
- a. treating said waste material with a 23% ammonium chloride solution at a temperature of at least 90.degree. C. to form a product solution which comprises dissolved zinc and dissolved zinc oxide whereby any iron oxide in said waste material will not go into solution;
- b. adding carbon to said product solution whereby said carbon will not go into solution;
- c. separating said product solution from any undissolved materials present in said product solution including any of said iron oxide and said carbon;
- d. adding zinc metal and a dispersant to said product solution whereby any lead and copper ions contained within said product solution are displaced by said zinc metal and precipitate out of said product solution as lead and cadmium metals and said dispersant is selected from the group consisting of dispersants which will prevent the aggregation of said zinc metal;
- e. separating said product solution from the lead and cadmium metals;
- f. lowering the temperature of said product solution in a controlled fashion over a predetermined period of time to a temperature of between about 20.degree. C. and 60.degree. C. thereby precipitating out said compounds of zinc, including diamino zinc dichloride and hydrated zinc oxide;
- g. separating said precipitated zinc compounds from said product solution;
- h. recycling said product solution after said zinc compounds are precipitated therefrom in step d to be employed in step b;
- i. washing said zinc compounds solids with a wash water at a temperature of between about 25.degree. C. and 100.degree. C. thereby solubilizing certain of said zinc compounds;
- j. concentrating said wash water after said zinc oxide is separated therefrom by the removal of pure water therefrom, and recycling said wash water to be employed in step i;
- k. separating the remaining zinc compounds solids from said solution;
- l. drying said remaining zinc compounds solids for between about 2 minutes and 60 minutes at a temperature of between about 100.degree. C. and 200.degree. whereby said resulting product is zinc oxide of 99% or greater purity;
- and
- m. forming said undissolved materials separated from said product solution into a cake comprising from 78 percent to 86 percent solids.
11 more elements
Dependencies are inferred from the claim text.