US 4,784,687 AGranted

Tungsten recovery

AssigneeInterox Chemicals Limited

InventorsDiana M. Anderson, Denis A. Hutton

Life of this patent

Estimating the term…

Loading patent…

Abstract

The scarcity of high grade tungsten ores obliges users to seek to recover it from scrap materials, but drill bits in particular pose especial problems. Existing proposals to use acidic hydrogen peroxide to oxides and solubilize tungsten is extremely inefficient in reagent consumption per unit tungsten recovered. According to the present invention, hydrogen peroxide can be used considerably more efficiently in the extraction of tungsten into an aqueous acidic solution by employing certain promoters which are solid at 50.degree. C. in the form of fused blocks. These blocks release the promoter slowly into the reaction solution and achieve similar efficiency of use of hydrogen peroxide and acid but at markedly reduced consumption of promoter in comparison with the same promoter added in powder or granular form. Examples of such promoter are hydroxy or amino substituted aromatic carboxylic acids e.g. 2-hydroxybenzoic acid. The promoters can most conveniently be used in a multi-stage tungsten extraction process.

Claims13

Dependent claims

In a process for the recovery of tungsten from pieces of tungsten alloy-containing material of at least 5 mm in size in which the pieces are contacted with an aqueous mineral acid solution of hydrogen peroxide at a temperature maintained at from 10.degree. C. to 50.degree. C. until at least some tungsten has passed into solution, the improvement which comprises contacting the aqueous acidic solution with a fused block weighing at least 30 grams of a promoter selected from the group consisting of:

(a) a compound having the formula:
##STR2## wherein A is a hydroxyl or an amine substituent, B is a carboxylic acid or an aldoxime group, and C is an optional further substituent selected from the group consisting of alkyl, hydroxyl, and amino groups;
(b) amino phenol;
(c) 1,4-benzoquinone;
(d) dihydroquinone;
(e) 1,3-dinitrobenzene acid;
(f) oxalic acid;
(g) epoxysuccinic acid;
and
(h) tartaric acid;
said promoters being solid at 50.degree. C., whereby consumption of the promoter is less than the amount that would be consumed if the same amount of promoter had been introduced in powder or granular form, under otherwise identical process conditions.

8 more elements

Dependencies are inferred from the claim text.