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Metals and the Environment

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Links to the 2011 specifications

AQA C1.3.1 – Extracting metals

Edexcel Topic 4 – Obtaining and using metals

OCR Gateway C2c – Metals and alloys

How Science Works

The content in this presentation can help illustrate how scientists:• use appropriate methodology to answer scientific questions and solve scientific problems• evaluate the use of contemporary scientific and technological developments and their

benefits, drawbacks and risks• consider how and why decisions about science and technology are made, including

those that raise ethical issues, and about the social, economic and environmental effects of such decisions.

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Bioleaching

New mining techniques can decrease the effects of metal extraction on the environment.

In bioleaching, metal ores are dissolved in a solution then mixed with certain bacteria. Depending on the type of bacteria, different metals will be ‘leached’ from the ores into the solution, ready for electrolysis or a displacement reaction.

Bioleaching uses less energy than traditional extraction and does not produce waste gases.

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Phytomining

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Extracting copper

Copper extracted from its ore by bioleaching or phytomining is impure. In order to purify the copper, it must be dissolved in an acid, such as sulfuric acid, then electrolysis carried out.

The copper from the copper sulfate solution is attracted to the pure copper negative electrode. Titanium is used for the positive electrode.

Copper can also be extracted from solutions of copper sulfate by carrying out a displacement reaction using scrap iron.