How can metals be extracted from sulphide ores

In the furnace, iron III oxide is reduced to molten iron when it reacts with carbon monoxide:. At the same time, limestone decomposes to form calcium oxide:. Calcium oxide is a metal oxide, and so it is a base. Calcium oxide reacts with silicon dioxide in the blast furnace.

Silicon dioxide is an impurity present in the iron ore. This reaction is a neutralisation reaction because silicon dioxide is a non-metal oxide, so therefore can react as an acid:. The product formed is often called 'slag'. This method of extraction works because carbon is more reactive than iron, so it can displace iron from iron compounds.

In cooper industry, Chalcopyrite CuFeS 2 is the most abundant and refractory copper-bearing mineral worldwide and also the principal mineral source from which copper is recovered commercially Xia et al.

That also converts it in the main copper sulphide mineral mined at bioleaching operations. However, even if bacterial activity is not facilitated, microbial assisted air oxidation of iron II and sulphur will contribute to copper extraction if sulphide minerals are present in a heap Watling, Thus, is important to know whether, for a given process and mineral, if there is one ideal combination of micro-organisms or whether combinations of different microbial isolates or species are likely to be as efficient as each other once they are equally adapted to the mineral in synergic activity.

The question arises, therefore, as to whether the microbial populations in commercial operations are the most suitable and efficient consortia and the most effective strains and species that could be used for processing different minerals Rawlings and Johnson, The objective of this study was isolate a bacterial consortium present in mineral composed mainly of chalcopyrite-bornite and determine which of this isolated consortiums was best suited for the extraction of copper from sulphide ore samples.

A single sample of sulphide ore was collected from the region of Atacama, Chile, specifically from the Mining Company El Abra. This mineral presented a mineralogy of 0. For the enrichment of the different bacterial species from the sulphide ore studied, were used mL Erlenmeyer flasks with mL of the culture medium for each bacterial species described by the following authors: Leptospirillum ferrooxidans Battaglia et al. Then, the flasks with enrichment media for the various species were incubated in a thermo regulated shaker Lab Line brand model No.

All cultures were grown at a stirring speed of 3. The above step was repeated for at least 10 times to achieve isolation of the different bacterial consortia Battaglia et al. For the measurement of copper extraction was performed a chemical analysis with an atomic absorption equipment Perkin Elmer model Once enriched the bacterial consortia present in the ore, we performed the method described by Xia et al.

Finally, it was performed a scaling on columns of 1. Data were analyzed by Software GraphPad Prism v. In these tests it was studied the ability of copper extraction by different bacterial consortia and their interaction with sulphide ore of a mining company. Figure 1 shows that the bacterial consortium that achieve a greater extraction of copper since day 10 until the end, was composed by At.

This is in line with the reported by Norris et al. However, this does not apply by combining the iron oxidizing bacteria L. In fact, the amount of copper extracted at the end of the test from each bacterium is the same compared to when they are combined. The consortium enriched for At. This may be due to the appearance of iron oxidizing bacteria during the development of the test, which were in the mineral surface and began to grow.

It must be taken into account that the industrial process does not require sterilization and will always exist native bacterial species on the mineral surface that may affect the behavior of the inoculated bacteria.

Also, by combining both bacterial consortia L. From this two bacteria, the most important is L. However, at the end of the test in Figure 2 , the consortium achieved a good extraction of copper, being in second place. Of this aspect, Klauber et al. Subsequently, Tshilombo et al. The layer would create a strong inhibition on the transfer of ferrous ions on the surface of this mineral polarized.

According to Dreisinger et al. Gold, silver, platinum and tin are insoluble in this electrolyte and so do not deposit on the cathode. Soluble impurities of iron and nickel dissolve in the electrolyte, which has to be continually purified to prevent excessive deposition onto the cathodes, which would reduce the purity of the copper.

Recently, stainless steel cathodes have replaced copper cathodes. Identical chemical reactions take place. Periodically, the cathodes are removed and pure copper is scraped off. This flow diagram summarises the sulfide ore processing stages. Find the two furnaces that send sulfur dioxide gas to the acid plant. Courtesy of Rio Tinto. Go to the download section to access zip files of all resources for each subject and age group for use offline.

Copper is infinitely recyclable without losing any of its properties. This means it is not consumed and can be used and re-used over and over again. Mining Metals Metals are often found as compounds in ores. Courtesy of Codelco. Web search hints: Porphyry copper — Nazca subduction — Global volcanism smithsonian Copper can be extracted from its ore by: Underground: sinking a vertical shaft into the Earth to an appropriate depth and driving horizontal tunnels into the ore.

Courtesy of BHP Billiton. Copper ore is loaded into trucks. In some mines these trucks have no driver. This truck carrying copper ore has no driver. It is guided by a GPS system. Can you see the GPS antenna? Ball mills crush the ore into a fine powder. This is a rare chance to see a mill and flotation building before the roof is built.

Froth flotation tanks. The roasting process: changes some of the CuFeS 2 to copper oxide removes some of the sulfur as sulfur dioxide This is done by heating the concentrated ore from froth flotation. Courtesy of Xstrata. SiO 2 slag This is very similar to the removal of impurities in the blast furnace. Blister copper from the smelter is poured into the anode casting moulds. The anodes are cast into slabs about 1 metre square with arms at the top corners for lifting.

The anode casting turntable moves slowly round. The anodes can be lifted out at the far side. Questions and Activities Place these products in the extraction process in ascending order of copper content.

Use the flow chart as a guide: Matte Ore Cathode copper Blister Anode copper Copper concentrate Fire refined copper Use a periodic table to find the atomic masses of the elements in cuprite and chalcocite.

Then work out the percentage of copper in each mineral. Which of the minerals in the table are sulfides? Why is sulfur dioxide scrubbed from the smelter flue gases?

Discover the Answers. Education Resource Menu. Correspondence to Wasim Sajjad. Reprints and Permissions. Sajjad, W. Trans Indian Inst Met 72, — Download citation. Received : 01 January Accepted : 07 November Published : 02 January Issue Date : 07 March Anyone you share the following link with will be able to read this content:.

Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search SpringerLink Search. Abstract Nowadays, due to fast global industrial progress and near diminution of high-grade ore reserves, there has been massive call to cost-effectively process the resources of low-grade ores and industrial effluents for metal extraction. References 1.