CS258589B1 - Method of phosphate glasses hydrolysis with silver content - Google Patents

Abstract

Process for phosphate glass hydrolysis silver and aluminum process efficiently and at low cost Waste these glasses, taking silver out as a readily processable halide silver, which is achieved by to glass containing at least 70 wt. in grain sizes up to 0.01 mm and less than 10% wt. other solid phases, is added to each phosphorus phosphion 0.1 to 3 mol water, the resulting mixture was heated to 45 ° C 100 ° C and then treated as an aqueous solution adds silver 1 to 5 per gram halide halogens and for each gramthion 1 to 9 gram equivalents of acid hydrochloric, sulfur and / or phosphoric .

Description

The invention relates to a process for the hydrolysis of silver-containing phosphate glasses suitable for the treatment of waste after cutting, milling and grinding of such glasses.

Photochromic phosphate glasses are composed of a number of ions, where phosphate ions predominate by weight. Along with alkali and silver ions, aluminum ions, which stabilize the glass against moisture, are significant. For the same reason, the decomposition of wastes of these substances is relatively difficult, although the grain size of these wastes is low. As a rule, concentrated sulfuric, phosphoric and / or alkaline hydroxides need to be used, requiring a considerable amount of other acids or alkaline reactants to neutralize.

This problem can be overcome by the method of hydrolysis of silver and aluminum phosphate glasses according to the invention, characterized in that the glass containing at least 70% by weight fractions up to 0.01 mm and less than 10% by weight fractions of other solid phases 0.1 to 3 moles of water are added per gram of phosphorus, the resulting mixture is heated to 45 to 100 ° C, and thereafter 1 to 5 gram of halide and optionally 1 to 9 gram of aluminum halide are added as an aqueous solution. % of hydrochloric, sulfuric or phosphoric acid.

The application of this small amount of water to the fine-grained glass, which is by far the predominant part of the waste from its treatment, releases phosphoric acid, which ensures the decomposition of the larger particles present. Completely large particles, usually above 2 to 3 mm, are only cleaned by the action of self-released phosphoric acid and can be used for remelting after simple mechanical separation. Another consequence of the addition of a small amount of water is the separation of most of the oily emulsions used in cutting and milling glass in coolants. After the hydrolysis, the time of which varies depending on the grain size of the glass to be treated and the temperature used, further decomposition can be carried out only with water, but the resulting aluminum hydroxide Al (OH) ₃ and aluminum orthophosphate AlPO4 produce hardly disintegrating pieces. This undesirable phenomenon is prevented by adding an acid and the halide ions, preferably in the form of hydrochloric acid to give a coarse-crystalline silver halide, contaminated with only small amounts of orthophosphate boron BPO _4, which arises under these conditions only a small amount, and a solution that can be removed by filtration or decantation and containing most of the constituents of the original glass, except silver. Without the addition of acids, silver can also be obtained from lump but hydrolysed glass by extraction with aqueous ammonia.

At the same time, in the hydrolysis of the glass, it is advantageous to use for each gram of phosphate in the decomposed glass an addition of 10 to 10 gram of the alkali metal salt of paraffin sulfone, thereby improving the wetting of the glass particles.

With the process according to the invention, silver-containing phosphate glass waste can be treated at low cost, the silver being separated as an easily workable silver halide.

Example 1

Phosphate glass, containing in 100 g 1.08 grams of phosphorus, 0.085 grions of boron, 0.073 grions of potassium, 0.21 grams of lithium, 0.138 grions of aluminum and 0.0225 grions of silver was processed by cutting. Kg 1 kg of cut waste consisting of 85% of grains up to 0.01 mm, 12 µs of grains over 0.01 mm and 3% of cutting oil, 8 grammol of water was added and the resulting mixture was kneaded. After 10 minutes an oil precipitated which was separated from the plastic mixture. The mixture was self-heated to 55 ° C and held at this temperature for 15 hours. Then the completely solidified mixture was broken up into pieces up to 5 cm in size, which were poured with a mixture of 4 grammolecules of hydrochloric acid and 24 grammolecules of water. After 48 hours, a clear solution was formed with an AgCl silver deposit contaminated with about equal amounts of boron orthophosphate BPO4. After filtration, the impure AgCl silver was dissolved in aqueous ammonia and silver was obtained therefrom by electrolysis. To the solution was added 5 g of sodium iodide NaJ, which dissolved small residues of dissolved silver chloride such as silver iodide AgJ. When only 0.3 grammol of hydrochloric acid was used, the final product consisted in part of sludge and in part of soft but not decomposed pieces. After filtration, the sludge and the pieces were washed with a mixture of 100 grammol of water and 10 grammol of ammonia. The resulting wash liquid contained all the silver present which was eliminated by the addition of nitric acid.

Example 2

The abrasive sludges of the same glass as in Example 1 consisted of 80% of glass grains up to 0.005 mm in size, 20% of water, i.e., per gram of phosphorus, there were 1.29 grammes of water. After addition of 1% by weight of sulfonated rapeseed oil, the sludge was heated to 90 ° C for 3 h. Then it was left without heating for 48 h. The treated sludge was hard and friable. 100 g of treated sludge containing 0.02 grams of silver and 0.11 grams of aluminum was mixed with 0.3 grammol of sulfuric acid, 0.06 grammol of sodium iodide in 15 grammol of water. After 3 h, a solution with deposited silver iodide and boron orthophosphate was formed. Silver was obtained from the deposit after reduction with an aqueous solution of formaldehyde and sodium hydroxide.

Claims (1)

Method for the hydrolysis of silver and aluminum phosphate glasses, characterized in that 0.1 to 3 phosphorus glasses for each gramion of at least 70% by weight in a particle size of up to 0.01 mm and less than 10% by weight of other solid phases are added. The resulting mixture is heated to 45-100 ° C and then 1 to 5 gram halides of silver halide and optionally 1 to 9 gram equivalents of hydrochloric, sulfuric and / or phosphoric acid are added as aqueous solution to each gram of silver.