Technology for extracting tellurium dioxide from tellurium-containing smelting slag

The invention relates to a technology for extracting tellurium dioxide from tellurium-containing smelting slag. The technology comprises the following steps: ball-milling tellurium slag, leaching by water, carrying out reduction alkali leaching, vulcanizing, carrying out silicon removal purification, and neutralizing to precipitate tellurium. The method has the advantages of tellurium leaching rate improvement, reduction of the alkali application amount in the leaching operation, and production cost reduction. The method is characterized in that sodium hydrosulphite is adopted as a transition agent to transit insoluble high-valence tellurium to low-valence tellurium, so the leaching rate leaching rate is increased. The total tellurium leaching rate can reach above 90% under a suitable technological condition; and after recovering tellurium through neutralizing, the TeO2 grade of the smelting slag can reach above 50%, and the content of tellurium in the waste liquid obtained after the neutralizing is 0.1-0.3g/L. The method also has the advantages of further enrichment of copper, lead, bismuth, antimony and precious metals in the leaching slag, realization of the resource reuse, production cost reduction, and energy saving, and is of great importance to the resource recovery and the environmental protection.