METHOD OF EXTRACTION AND CONCENTRATION OF THORIUM OUT OF SPENT MELT OF SALINE SPRINKLER FILTER - PROCESS WASTE OF CHLORINATE TREATMENT OF LOPARIT CONCENTRATE Russian patent published in 2008 - IPC C22B60/02 C22B34/24 C22B3/04 

FIELD: metallurgy.

SUBSTANCE: invention refers to extraction and concentration of thorium out of process waste of loparit concentrates treatment - spent melt of saline sprinkler filter (SSF) of loparit concentrate chlorination process. The method includes preparation of suspension by means of discharge of spent melt of saline sprinkler filter (SSF) into water, incorporation of high molecular flocculant, of holding, filtering, separation of sediment, obtaining of chloride solution, and of treatment with steel scrap and metal magnesium. Prior to obtaining chloride solution the source suspension is heated to 60-90°C and treated with solution of sodium hydroxide to pH 1.5-2.0 and to 0.1-0.3% solution of high molecular flocculant at amount of 3-5% from the source volume of suspension; then suspension is held for 2-4 hrs. Chloride solution is received by means of filtration of spent suspension obtaining sediment of rare metals; chloride solution is then treated with steel scrap and metal magnesium; at that the solution is successively treated first with the steel scrap at amount of 3-5 mass fractions of iron per 1 fraction of iron ions (III) in chloride solution at 80-100°C for 1-3 hrs till achieving the value of pH in a pulp equal to 3.0-3.5. Then the pulp is separated from the non-reacted portion of the steel scrap and is treated with metal magnesium to pH 3.5-4.5, and further with 0.1-0.3% solution of high molecular flocculant taken at amount of 5-20% from the volume of chloride solution. Thus produced pulp is held without mixing for 1-4 hrs and filtered producing thorium containing sediment; the said sediment is washed at filter first with solution containing 1-5 g/dcm³ of sodium sulphite, then with water. Washed out sediment is repulped in solution of sodium hydroxide with concentration of 50-150g/dcm³ at a ratio of "Ж:Т"=3-5 at 60-90°C for 2-3 hrs, after what the pulp is filtered with separation of alkaline filtrate. Thorium containing sediment at the filter is washed with water, pressed at the filter and dried; the alkaline filtrate and process water are merged and mixed, then heated to 80-90°C, and treated with solution of sodium hydroxide to pH 11-13 with production of hydroxide pulp. Hydroxide pulp is filtered and then radioactive sediment is produced at the filter; it is washed out with water and transferred to a special wastes depositary, while filtrate is mixed with 10-20 volumes of shop flush water, heated to 80-90°C and again treated with solution of sodium hydroxide to pH 11-13. Obtained pulp is held and filtered thus producing sediment of rare metals and deactivated chloride solution which is discharged to drainage. Sediment of rare metals is unloaded from the filter, merged with sediment of rare metals extracted from the source suspension, dried, washed out and then transferred for preparation of charge for its further chlorination together with the loparit concentrate.

EFFECT: upgraded efficiency of thorium extraction and simultaneously solving problem of neutralisation and utilisation of process waste.

1 dwg, 1 ex