How Is Copper Obtained From It Ores?

Simply heating in air

Copper is far down the reactivity series. It is found "native" (uncombined) in some parts of the world. It is also mined as the sulphide. This is roasted in air to give impure copper. Pure copper is obtained from an electrolytic method which is listed below.

The electrolyte in the electrolytic cell is copper (II) sulphate. The negative electrode is a strip of pure copper. The positive electrode is a lump of impure copper.

After the cell has operated for a week, the negative electrode becomes very think. It is lifted out of the cell, and a new thing sheet of copper is put in its place. When all the copper has been removed from the impure slab of metal which forms the positive electrode (the anode), a new piece of impure copper is substituted. Undissolved matter from the old anode lies on the bottom of the cell as anode sludge.

Any impurities in the copper are likely to e metals such as iron and zinc, which are more reactive than copper. Their ions stay in solution while copper ions are discharged. Metals which are less reactive than copper, that is silver and gold, accumulate in the anode sludge. They can be extracted from this material.

Copper is commonly extracted from sulphide ores such as chalcopyrite. Chalcopyrite is also known as copper pyrites. The chemical formula for chalcopyrite or copper pyrites is CuFeS2, which means that chalcopyrite is a compound made up of three elements, namely copper, iron and sulphur. Sulphide ores, however, they are not the only type of ores from which copper can be extracted. It is also obtained, by different methods, the ores have a low percentage of copper, and the froth floatation method is used for the concentration of the ore before it is refined.

Copper is extracted from its sulphide ore by first heating it strongly with silicon dioxide or silica and oxygen (air) in a series of furnaces. The copper (II) ions in the chalcopyrite are converted to copper (I) sulphide and further to copper metal in the final stage of the extraction process. The iron in chalcopyrite gets converted into an iron (II) silicate slag, which gets removed. The sulphur in the chalcopyrite gets converted into sulphur dioxide gas, and this is turn is used to make sulphuric acid via the contact process. The formula for this process is 2CuFeS2 + 2SiO2 + 4O2  Cu2S + 2FeSiO3 + 3SO2. The copper (I) sulphide produced is converted to sulphur with a final blast of air. Cu2S + O2  2Cu + SO2. The end product of this is known as blister copper. Blister copper is about 98 to 99.5 per cent pure and is a porous, brittle form of copper.