Rare Metal Extraction Program

Rare Metal Extraction Program

Talk about recycling and reinventing! Three hundred eight-six Honda hybrid vehicles stored for sale were made unusable by the March 2011 earthquake that led to a devastating tsunami. But all was not lost. The rare metal from nickel-metal hydride batteries could be extracted and put to new use.

Extracting rare metals from the earth involves mining and the environmental impact the process entails. But reusing them can help curb demand by companies that need them. Japanese automaker Honda is spearheading a process to reuse rare earth metals extracted from nickel metal hydride batteries for new ones in a bid to preserve precious and finite resources.

The initiative has been put in place at the plant of Japan Metals & Chemicals (JMC), where Honda has been extracting an oxide containing rare earth metals from used nickel-metal hydride batteries. Honda has succeeded in extracting metalized rare earth that can be used directly as negative-electrode materials for those batteries.

The good news is that the rare earth metals extracted in this process have a purity of more than 99%, which is as high as that of ordinary traded, newly mined rare earth metals. In addition, the new process enables the extraction of as much as above 80% of rare earth metals contained in nickel-metal hydride battery.

Starting early March, the extracted rare earth metals are being supplied from JMC to a battery manufacturer, which will reuse them as negative-electrode materials for nickel-metal hydride batteries for hybrid vehicles. This first batch came from the vehicles rendered useless by the earthquake.

The plans go further. As soon as a sufficient volume is secured, Honda said it will begin applying the same process and recycle rare earth metals extracted from used nickel-metal hydride batteries collected by Honda dealers through battery replacement.

Honda said it will try to extract rare earth metals not only from nickel-metal hydride batteries but also from various used parts to increase the volume of material being recycled.

WHO IS VERY IMPORTANT MATERIALS

VERY IMPORTANT MATERIALS

The extraction and manufacture of aluminium and sodium are described. The extraction, smelting and purification of copper is covered and similarly notes on the extraction of zinc, titanium and chromium. How to extract a metal is one technological issue, but finally some economic and environmental Issues and metal recycling are discussed as a result of metal extraction. Below is the index of revision notes on extraction procedures and theory, so, scroll down for revision notes on extraction procedures and theory which should prove useful for school/college assignments/projects on ways of extracting metals from their ores.

A vast array of raw materials, including minerals and 'high-tech metals', play a key role in the development of industrial applications and advanced consumer products. According to a recent report by an expert group in the framework of the EU Raw Materials Initiative, Europe is in a vulnerable position when it comes to securing its supply of some of these raw materials: out of 41 minerals and metals analysed, the experts labelled 14 as critical. The results of the report will be used in the drafting of strategies to ensure access to raw materials which the European Commission will present in autumn 2010.
'Critical raw materials for the EU  [2 MB] ' was written by an ad hoc working group, chaired by the European Commission and made up of experts from national ministries, geological surveys and industry. The report was an important step towards achieving the objective of defining critical raw materials, as outlined in the EU's Raw Materials Initiative (see box).

After analysing 41 minerals and metals, the team produced a list of 14 raw materials which they deemed critical to the EU: antimony, beryllium, cobalt, fluorspar, gallium, germanium, graphite, indium, magnesium, niobium, platinum group metals, rare earths, tantalum and tungsten. Forecasts indicate that demand for some of these could more than triple by 2030, compared to 2006 levels.

Demand is increasing for minerals and 'high-tech metals' due to the economic growth of developing countries. The emergence of new technologies and products also drives demand. For example, flat-screen TVs and mobile phones need metals, such as antimony, cobalt, lithium, tantalum and tungsten. Many of the new environmentally friendly products also need these raw materials. Electric cars require lithium and neodymium; car catalysts cannot work without platinum; and solar panels are developed using gallium and indium.

Increasing demands on supply

Risks to reliable supplies to Europe come from fast-growing emerging economies, especially those which are blessed with their own deposits of minerals and metals. Now that a number of these countries are pursuing ambitious industrial development strategies, they are beginning to reserve more and more of these resources for their own use. Government measures, such as export taxes, quotas and subsidies are being used in a way that distorts the trade of raw materials on world markets.

Supply risk issues are compounded by the fact that production of some critical raw materials is often concentrated in a few countries. For instance, China produces more than 90% of the world's rare earths and antimony, about 90% of niobium comes from Brazil, and 77% of platinum comes from South Africa.

The nature of mining for these raw materials also has to be taken into account. They are often produced as by-products through the mining and processing of major metals like copper and zinc, which mainly drive their extraction. This can leave industry facing a crisis of availability, as happened in 2000 when there was a rush for tantalum due to the boom in mobile phone production.

The report also noted that the EU has its own valuable but under-exploited deposits of minerals and metals. However, exploitation and extraction is hampered by competition from other land-use needs, and mining regulations can make the transition from discovery to extraction a slow process.

"We need fair play on external markets, a good framework to foster sustainable raw materials supply from EU sources as well as improved resource efficiency and more use of recycling," said European Commission Vice-President Antonio Tajani, in charge of Industry and Entrepreneurship.

Gauging "criticality"

When considering whether a raw material is critical, the Group assessed two types of risk. Supply risk took account of the political and economic stability of the producing countries, along with levels of production concentration, whether any substitute materials are readily available, and rates of recycling. Similarly, the environmental country risk took account of environmentally related risks.

The report makes a number of policy recommendations to help improve supply of critical raw materials and so minimise the risk of shortages.

More raw data

In addition to updating the critical list every five years, the Group suggests efforts should be made to improve the information that is available on raw materials. It also wants to see more research into the life-cycles of raw materials and the products they are used in.

Access to primary resources will have to improve to ensure supply. In the EU that will require fair treatment of mining and extraction compared with other forms of land use. And more needs to be done to promote sustainable exploration in and outside Europe.

The EU will have to make sure that it keeps a close eye on trade and investment activities which hamper the smooth functioning of international markets for raw materials.

More must be done to improve the efficiency of recycling of raw materials. This means an end to stockpiling at home, dumping in landfills and incineration. Promoting more research on ways to optimise recycling could help bring about positive change.

The Group also recommends that efforts should be made to find substitutes for some of these critical metals and minerals. Research in this area could be promoted under EU framework programmes.

General Principles of Extraction of Metals

The powdered ore is suspended in a stream of water. The heavier ore particles collect behind the riffles and the gangue particles are carried away with the stream of water. Hydraulic classifier is shown in this. Powdered ore is dropped from the top of classifier and strong stream of water is introduced from the bottom. The lighter gangue particles are carried away by the water while the heavier ore particles settle down. Generally, Oxide and carbonate ores are concentrated by this method. For example, tin ore (cassiterite) and iron ore (haematite) are concentrated by gravity method.
Metals occur in nature sometimes free but mostly in combined state. The natural mode of occurrence of a metals is largely dependent on its nature. Those metals which are least reactive and have little or no affinity for oxygen, moisture and other chemical reagents occur in free or metallic or native state i.e., in uncombined state. Most of the metals are reactive and hence are found in combined state i.e., as compounds.
The natural substances in which the metals or their compounds occur in the earth are called minerals. The mineral has a definite composition. It may be a single compound or a complex mixture. The minerals from which the metals can be conveniently and economically extracted are known as ores. All the ores are minerals but all minerals cannot be ores. For example, both bauxite (Al2O3. 2H2O) and clay (Al2O3.2SiO2.2H2O) are minerals of aluminium. It is bauxite which is used for extraction of aluminium and not clay. Thus, bauxite is an ore of aluminium. Ores may be divided into four groups.

Native ores : These ores contain metals in free state, e.g., silver, gold, platinum, mercury, copper, etc. These are found usually associated with rock or alluvial materials like clay, sand, etc. Sometimes lumps of pure metals are also found. These are termed nuggets.

Oxidised ores : In these ores. Metals re present as their oxides or oxysalts such as carbonates, nitrates, sulphates, phosphates, silicates, etc.

Halide ores : Metallic halides are very few in nature. Chlorides are most common.


2. METALLURGY:

The whole process of obtaining a pure metal from one of its ores is known as metallurgy.
In order to extract the metal from ores, several physical and chemical methods are used. The method used depends upon the nature of the ore, the properties of the metal and the local conditions, Thus, it is not possible to have a universal method for the extraction of all the metals from their ores.  However, the metallurgy of a metal involves three main operations:

Concentration or dressing of Ore,

Reduction of Ore

Purification or refining of Ore


Concentration or dressing of ores: Ores usually contain soil, sand, stones and other useless silicates. These undesired impurities present in ores are called Gangue or Matrix. The removal of these impurities from the ores is known as concentration. Before the ore is subjected to concentration, it is crushed into small pieces in gyratory crushers. The crushed ore is then grinded with the help of rollers or in the stamp mill to powder form.


Physical Methods

The following physical methods are generally employed for the concentration of the ores depending upon the nature of the ore.

Gravity separation : The separation is based on the difference in the specific gravities of the gangue particles and the ore particles. The powdered ore is agitated with water or washed with a running stream of water. The heavy ore particles settle down while the lighter particles of sand, clay, etc., are washed away. For this either Wilfley table is used. It a wooden table having slanting floor on which long wooden strips called riffles are fixed.

Types of Extraction Metals

Many metals are found in the Earth's crust as ores. An ore is usually a compound of the metal mixed with impurities. When the metal is dug up, a method must be used to separate the metal from the rest of the ore. This is called extracting the metal.

The method of extraction depends on how reactive the metal is. The more reactive the metal, the more difficult it is to extract from its compound.

Electrolysis

Electrolysis is the most powerful extraction method. But it takes a lot of electricity and that makes it expensive. Hence, electrolysis is only used for the most reactive metals.

Metal: Method of extraction:
Potassium Electrolysis
Sodium Electrolysis
Calcium Electrolysis
Magnesium Electrolysis
Aluminium Electrolysis
Zinc Heat with carbon or carbon monoxide
Iron Heat with carbon or carbon monoxide
Lead Heat with carbon or carbon monoxide
Copper Roasting in air
Silver Occur naturally
Gold Occur naturally
Examples of the different methods of extraction

Electrolysis: Used in extracting aluminium and extracting sodium from rock salt.

In the case of the rock salt, it is first melted in giant steel tanks:



The extraction of aluminium is dealt with in a separate learn its within this topic.

Heating with Carbon monoxide: Used for extracting iron from iron ore using the blast furnace.



Roasting in Air: Used in extractingcopper from copper (I) sulphide (copper pyrites).



The copper is extracted by roasting the ore in air.

Recycling metals

Metals are non-renewable resources. This means once dug up it cannot be replaced. Hence, the supply will eventually run out.

For example: it is expected that tin will run out within the next 15 years and copper in the next 40 years! Therefore,the recycling of these two useful metals and others such as iron and aluminium is most important.

In recycling, metals are melted down before reshaping into their new use. However, this can be costly. Recycling companies will only recycle if it is economical!

Pyrometallurgy

Pyrometallurgy involves high temperature processes where chemical reactions take place among gases, solids, and molten materials. Solids containing valuable metals are reacted to form intermediate compounds for further processing or converted into their elemental or metallic state. Pyrometallurgical processes that involve gases and solids are typified by calcining and roasting operations. Processes that produce molten products are collectively referred to as smelting operations. The energy required to sustain the high temperature pyrometallurgical processes may come entirely from the exothermic nature of the chemical reactions taking place, usually oxidation reactions. Often, however, energy must be added to the process by combustion of fuel or, in the case of some smelting processes, by the direct application of electrical energy.
Ellingham Diagrams are a useful way of analysing the possible reactions, and so predicting their outcome.

Hydrometallurgy

Hydrometallurgy is concerned with processes involving aqueous solutions to extract metals from ores. The most common hydrometallurgical process is leaching, which involves dissolution of the valuable metals into the aqueous solution. After the solution is separated from the ore solids, the solution is often subjected to various processes of purification and concentration before the valuable metal is recovered either in its metallic state or as a chemical compound. The solution purification and concentration processes may include precipitation, distillation, adsorption, and solvent extraction. The final recovery step may involve precipitation, cementation, or an electrometallurgical process. Sometimes, hydrometallurgical processes may be carried out directly on the ore material without any pretreatment steps. More often, the ore must be pretreated by various mineral processing steps, and sometimes by pyrometallurgical processes.

Mineral processing

Mineral processing

Mineral processing involves the processes used to manipulate the particle size of solid raw materials and to separate valuable materials from materials of no value, referred to as gangue. Usually, particle size reduction, also referred to as comminution, is required to permit efficient separation of the valuable materials from gangue. Separation processes take advantage of physical properties of the materials in order to separate them from each other. These physical properties can include density, particle size and shape, electrical and magnetic properties, and surface properties. Since many size reduction and separation processes involve the use of water, solid-liquid separation processes are also a subject of mineral processing.