Title of Invention

A PROCESS FOR RECOVERING COPPER FROM COPPER CONTAINING CONVERTER SLAG

Abstract

This invention relates to a process for the recovery of copper from converter slags. Converter slag is treated with pig iron under oxidative conditions to release entrapped copper therefrom. This mixture is allowed to settle. Copper separated is removed and may be refined subsequently. Valuable copper is recycled and saved from slag which increases the productivity of the plant and reduces environmental hazards due to dumping of copper containing waste.

Full Text

This invention relates to a process for recovering copper from copper containing converter slag. Copper is extracted from its ores through different stages. Naturally occuring ore which may be low in copper concentration is subjected to various steps of separation and concentration to increase its copper content and to reduce contamination. Concentrated ore containing a higher percentage of copper obtained after purification and separation is subjected to extraction of copper and subsequent refining. The raw copper ore input material normally contains about 30% of copper, the balance being iron, sulphur and other contaminents. Extraction normally consists of smelting in a furnace. Iron and sulphur present in the ore are removed by oxidation. Iron is converted into Ferrosilicate slag and sulphur is oxidised to sulphurdioxide which is utilized to sulphuric acid plants to produce sulphuric acid. Smelting is a continuous process and the molten metal which settles at the bottom of the furnace while slag forms the top part. The molten metal contains about 60 to 63% of copper and is taken out from the bottom of the fiimace from time to time. Slag is also removed periodically from the furnace. Matte and slag taken out from the smelting furnace are transferred to a rotary holding furnace where it is allowed to settle. Once sufficient matte is accumulated, it is taken out into laddies and transferred through electrical overhead travel cranes to a converter for further treatment. The slag is removed from the furnace to a slag granulation system for granulation and disposal. The off-gases from the rotary furnace are scrubbed with aqueous calcium hydroxide solution to remove sulphur dioxide contamination therefrom. In the last extraction stage blister copper containing about 98% of copper is obtained by oxidising the matte produced at the previous extraction stage. Sulphur dioxide produced during this extraction step is also led to sulphuric acid plant while iron contamination is removed as fayalite slag. This oxidation is carried out in a converter and air is conventionally used as the oxidising agent. "Blister copper" containing 98% of copper is then refined in an anode furnace in two stages, first by oxidation and then by reduction. The product obtained is called anode copper and has 99.5 % purity. In the above described copper extraction process, slag obtained from the converter containing approximately 10-15% copper and above 15 to 20% furic oxide is cooled, granulated and treated as waste product. It is an object of this invention to recover copper from converter slag by recycling the same to the rotary holding furnace. Furnace is charged with the slag and pig iron is added thereto under conventional oxidative conditions. Pig iron containing approximately 4% carbon reacts with the slag as shown below: Fe304 + Fe -> 4FeO 2Fe304 + C -> 6FeO + C02 During the reaction, copper content outrapped in Fe304 of the slag gets released and are easily separated because of the density difference with the slag sufiQcient time is allowed for the matte produced to settle from the slag which may be separated. Copper loss through slag formation in this recycled process is only as lov^f as 0.87. This invention relates to a process for recovering copper from copper containing converter slag which comprises reacting slag from copper extraction converters with pig iron under known oxidative conditions to oxidise said iron and to release. Copper entrapped in said converter slag, which is subsequently separated and recovered. This process is carried out in the existing copper extraction plant. The converter slag is treated with pig iron in the rotar" holding furnace which is provided with oxy-fuel burners. The shell of the furnace has a matte spout and a slag spout for draining the matte and slag from the molten residue. For each batch of converter slag loaded into the furnace, approximately 1 to 1.2 T of pig iron is introduced. The furnace temperature is maintained around 1200°C. Thus process of recycling slag from the converter to the rotary furnace may be carried out continuously as an integrated part of copper extraction as shown below. Smelting furnace -> rotary holding furnace -> -» converter -> 98% Blister copper Cu matte Recycled with pig Iron under oxidative conditions Slag waste Slag For continuous recycling the conventional rotary holding furnace may be provided with means for charging pig iron thereinto. Additional platform and means for lifting and handling pig iron may also be provided. This process avoids loss of valuable copper by improving copper recovery from the ores. Further more waste disposal of the slag is less hazardous as copper has substantially been removed. WE CLAIM: 1. A process for recovering copper from copper containing converter slag comprising reacting slag from copper extraction converters with pig iron under known oxidative conditions to oxidise said iron and to release copper entrapped in said converter slag which is subsequently separated and recovered. 2. The process as claimed in claim 1, wherein said converter slag is charged into a rotary holding furnace and pig iron added thereto under oxidative conditions. 3. The process as claimed in claims 1 and 2, wherein the mixture of converter slag and pig iron is heated to about 1200°C. 4. The process as claimed in claims 1-3, wherein on completion of the reaction, the reaction mixture is allowed to settle and having copper containing bottom portion is separated from the slag. 5. The process as claimed in claims 2 to 4, wherein said converter slag is recycled to said rotary holding furance continuously. 6. A process for recovering copper from copper containing converter slag substantially as herein described.

Documents:

0765-mas-2001 abstract-duplicate.pdf

0765-mas-2001 abstract.pdf

0765-mas-2001 claims-duplicate.pdf

0765-mas-2001 claims.pdf

0765-mas-2001 correspondence-others.pdf

0765-mas-2001 correspondence-po.pdf

0765-mas-2001 description (complete)-duplicate.pdf

0765-mas-2001 description (complete).pdf

0765-mas-2001 form-1.pdf

0765-mas-2001 form-18.pdf

0765-mas-2001 form-26.pdf

0765-mas-2001 form-3.pdf