Process for treatment of selenium-bearing materials
AssigneeInco Limited
InventorsGrigori S. Victorovich, Ramamritham Sridhar, Malcolm C. E. Bell
Life of this patent
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Abstract
Selenium-bearing materials are treated to convert selenium values to water-soluble form in a process which comprises producing a wet pellet product of uniform composition having a specified moisture content and size from an aqueous slurry containing the selenium-bearing material and dissolved sodium carbonate-containing reagent. In a preferred embodiment the slurry is pH-adjusted to neutralize free acid and/or to precipitate nonferrous base metals. sp This is a continuation of application Ser. No. 151,349 filed May 19, 1980, abandoned.
Claims25
In a process for treating a selenium-bearing material to convert selenium values to water soluble form, the improvement which comprises forming an aqueous slurry of the selenium-bearing material;
- adding a sodium carbonate-containing reagent to the slurry, the water content of the resultant slurry being at least 30% by weight, based on the total weight of the slurry, and at least sufficient to dissolve a preponderant part of the sodium carbonate-containing reagent;
- continuously feeding the resultant slurry to a heated pelletizing means to form pellets from the resultant slurry, said pelletizing means having a hot agitated pellet bed and said pellet bed being maintained at a temperature of between about 60.degree. C. and about 120.degree. C. during formation of the pellets;
- and maintaining a residence time of said pellets in the heated pelletizing means sufficient to produce a wet pellet product having a pellet size not greater than about 30 mm.
In a process for treating a selenium-bearing material, which may contain one or more of the values selected from tellurium, silver and nonferrous base metals such as copper, nickel, cobalt and lead, by roasting with soda ash to convert selenium values to a water soluble form, the improvement which comprises:
- a. forming a slurry of the selenium-bearing material in an aqueous medium;
- b. adjusting the pH of the slurry to neutralize free acid (if present), and precipitate nonferrous base metals (if present);
- c. adding a sodium carbonate-containing reagent to the slurry in an amount to provide a final slurry containing sodium;
- selenium+tellurium (if present) in a molar ratio of about 1.8:1 to about 3:1, the water content of said final slurry being at least 30 wt. % and at least sufficient in an amount to dissolve a preponderant amount of the sodium carbonate-containing reagent;
- d. continuously feeding the final slurry to a heated pelletizing means to form pellets from the slurry, said pelletizing means having a hot agitated pellet bed and said pellet bed being maintained at a temperature of between about 60.degree. C. and 120.degree. C., and maintaining a residence time of the pellets on the heated pelletizing means sufficient to produce a wet pellet product having a pellet size not greater than about 30 mm and having a moisture content of at least about 10% by weight;
- and
- e. drying and then roasting the wet pellet product, the roasting being carried out in an oxygen-containing atmosphere at a temperature of about 350.degree. to 500.degree. C. to convert selenium values to a water soluble form.
Dependencies are inferred from the claim text.