how is bioleaching used to extract copper

To speed up the process in a biomining lab, scientists use bioleaching. Ores are placed into acid, and then researchers introduce bacteria that change the solution so that it dismantles the rock and frees copper, in liquid form.

Full Answer

How do you extract copper from a leachate?

The solution is called a leachate and the process is called bioleaching. Bioleaching can be used to extract copper metal. It does not need high temperatures, but it produces toxic substances, including sulfuric acid, which damage the environment. Iron is more reactive than copper. It can displace copper from the leachate.

How to have an idea of bioleaching?

To have an idea of bioleaching process copper leaching by bacteria is described as an example. Covellite, chalcocite and chalcopyrite are generally used as copper ores for bioleaching processes. Apart from containing copper, the ores also contain other elements like iron, zinc and sulphur.

What is the leaching process for copper?

Leaching Method. The GEOCOAT™ Process - A heap leaching process that is capable of bioleaching copper concentrates. It does this by coating the concentrate slurry onto a support rock, or substrate material, and stacking this coated material in a bioxidation heap. The support rock itself may be a low-grade copper ore.

What are the copper ores for bioleaching?

Covellite, chalcocite and chalcopyrite are generally used as copper ores for bioleaching processes. Apart from containing copper, the ores also contain other elements like iron, zinc and sulphur. For example – Chalcopyrite contains 26% copper, 25.9% iron, 20.5% zinc and 33% sulphur.

How are metals extracted with bioleaching?

Direct bioleaching uses minerals that are easily receptive to oxidation to create a direct enzymatic strike using the microorganisms to separate the metal and the ore. In indirect bioleaching, microorganisms are not in direct contact with minerals during the process.

What method of extraction is used for copper?

Copper mining is usually performed using open-pit mining, in which a series of stepped benches are dug deeper and deeper into the earth over time. To remove the ore, boring machinery is used to drill holes into the hard rock, and explosives are inserted into the drill holes to blast and break the rock.

Is leaching used in extraction of copper?

The process uses low temperature pressure oxidation to directly leach copper from the ore followed by SX/EW of copper from the resulting leach solution. The plant operation achieved an annualized copper production of 50,000 tonnes Cu as LME grade cathode in 2002.

Which method is used in bioleaching of copper on laboratory scale?

At present bioleaching is used essentially for the recovery of copper, uranium and gold, and the main techniques employed are heap, dump and in situ leaching. Tank leaching is practised for the treatment of refractory gold ores.

How is copper mined and extracted?

It is primarily mined through open-pit or underground mining techniques. Open-pit mining, which accounts for approximately 90% of copper production, extracts ores near the earth's surface via graduated steps that lead into the earth's crust.

What is copper leaching?

October 2019) Heap leaching is an industrial mining process used to extract precious metals, copper, uranium, and other compounds from ore using a series of chemical reactions that absorb specific minerals and re-separate them after their division from other earth materials.

How is bioleaching used?

Bioleaching. Certain bacteria can break down ores to produce an acidic solution containing copper(II) ions. The solution is called a leachate and the process is called bioleaching . Bioleaching does not need high temperatures, but it produces toxic substances, including sulfuric acid, which damage the environment.

Which species is used in copper bioleaching?

The most well-known and first identified bioleaching bacteria are Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, and Acidithiobacillus thiooxidans.

What chemical is in copper leaching?

Sulfuric AcidCopper: Sulfuric Acid is used for leaching of copper from oxide ore, and some sulfide ores. The leaching solution is claimed to be diluted and recycled. However, it is recycled into lined ponds of high toxic levels of sulfuric acid.

Why are biological methods being introduced to extract copper?

reduces the need to obtain new ore by mining. conserves limited supplies of high-grade ores. reduces the amount of rock waste that must be disposed of after traditional mining.

What type of reaction is involved in bioleaching?

Copper(II) sulfate solution is produced and is carefully collected. This solution is called a leachate and the process is called bioleaching . Copper may be extracted from the copper(II) sulfate by a displacement reaction with iron or electrolysis .

Is copper extracted by reduction?

Extraction methods Copper(II) oxide is reduced as carbon is oxidised , so this is an example of a redox reaction. The impure copper is purified by electrolysis.

Where is copper extracted from?

In South America, Chile, the world's largest producer, and Peru are both major producers of copper. Large copper deposits are also found in Canada, the Ural Mountains of Russia, and parts of Africa.

How is copper extracted from electrolysis ore?

2:235:14How To Use Electrolysis & Smelting to Extract Copper (H) - YouTubeYouTubeStart of suggested clipEnd of suggested clipEach cu2 plus ion gains two electrons to become copper atoms over a period of time. This is theMoreEach cu2 plus ion gains two electrons to become copper atoms over a period of time. This is the result of the electrolysis of impure copper.

Why is copper purified using electrolysis?

1 Answer. Electrolysis of copper transfers copper atoms from an impure copper anode to a pure copper cathode, leaving the impurities behind. Unrefined copper is about 99 % pure. It contains traces of metals such as Fe, Zn, Ag, Au, and Pt.

How does bioleaching work?

Bioleaching involves the use of microorganisms to catalyze the oxidation of iron sulfides to create ferric sulfate and sulfuric acid. Ferric sulfate, which is a powerful oxidizing agent, then oxidizes the copper sulfide minerals and the copper contained is then leached by the sulfuric acid formed. In the case of uranium, the ferric sulfate oxidizes tetravalent uranium oxide, which is insoluble in acid, to hexavalent uranium oxide, which is then leached by the sulfuric acid. In biooxidation of refractory gold ores bacteria are used to oxidize, and therefore make soluble, an iron sulfide matrix in which the gold particles are imbedded and thus make the gold available for cyanide leaching. Likewise, in coal desulfurization, bacteria are used to oxidize the pyrite contaminant in the coal thus making the sulfur soluble as ferric sulfate.

What is bioleaching in science?

Bioleaching is the extraction of a metal from sulfide ores or concentrates using materials found native to the environment; namely , water, air and microorganisms. In other words, bioleaching is the commercialization of the ability of certain bacteria and archaea, found in nature, to catalyze the oxidation of sulfide minerals.

What are the bacteria used in bioleaching?

As indicated above, the original bacteria used in bioleaching were those that were native to the site where the leaching took place. However, once bioleaching gained acceptance as a potentially viable method for the recovery of metals from low-grade ores, flotation tailings and waste materials, efforts were undertaken to optimize the bacteria for the operation intended. "Native" bacteria, sometimes termed mesophilic bacteria, are sensitive to elevated temperatures and to some of the metals being extracted. Thus, microorganisms were sought that can withstand higher temperatures, thermophilic (and even hyperthermophilic; i.e., 60°C or higher) microorganisms, and are tolerant to the metals being extracted. One of the first locations to be investigated for suitable thermophilic bacteria was the hot springs at Yellowstone National Park. Others have been a hot spring in Iceland, a coalmine in Western Australia, a volcano in Italy and a slagheap in Germany.

How is copper produced?

Approximately 20% of all copper now produced worldwide is produced by leaching predominantly oxide ores. An undetermined amount of copper is currently recovered from sulfide ores through the aid of naturally occurring microorganisms. If costs can be lowered equivalent to that of the smelting process itself, bioleaching holds promise for the treatment of copper concentrates in situations wherein the capital costs of a smelter are not warranted and/or environmental considerations preclude smelting at that location. With the recently developed technologies that are now under test in demonstration trials and ongoing research into improved technologies, we can safely predict that bioleaching will eventually contribute to an increasing fraction of the copper produced each year.

What is the process of oxidation of sulfide minerals?

An associated process is biooxidation. This is the oxidation of sulfide minerals associated with but not necessarily part of the mineral of interest to be extracted.

What is the most abundant mineral in bioleaching?

Chemistry of Bioleaching. The majority of copper minerals are sulfides, with chalcopyrite (CuFeS2) being the most abundant and thus economically the most important. Others of economic importance are bornite (Cu 5 FeS 4 ), chalcocite (Cu 2 S) and covellite (CuS).

Is bioleaching a natural process?

Since bioleaching is a natural process, one undesirable effect is the creation of metalliferous acid drainage from the slow weathering of sulfide mineral outcrops and from abandoned mines. However, as in the case of Rio Tinto, in Spain, even this can be turned into an asset by recovery of the copper from such waters.

Where is copper bioleaching used?

Bioleaching of copper has been used in the United States, Australia, Canada, Mexico, South Africa, Portugal, Spain and Japan. About 5% of the world copper production is obtained through bioleaching.

How is copper leaching done?

The solution (Sulphate/Fe 3 solution) is sprinkled over the heap which percolates through the ore and collects at the bottom pit. The solution collecting in the bottom pit will include copper metal, which is removed by precipitation. The remaining water with Fe 3+ is used again in the leaching process after adjusting the pH to 2.0 with the help of H 2 SO 4. An outline of microbial leaching of copper is illustrated in Fig. 12.2.

What is the water used for after extraction of minerals?

The water after extraction of minerals, is reused after regeneration of bacteria. ii. Copper Leaching: To have an idea of bioleaching process copper leaching by bacteria is described as an example. Covellite, chalcocite and chalcopyrite are generally used as copper ores for bioleaching processes.

What is the purpose of ore leaching?

Ore leaching by microbes has potential for use in the extraction of other metals such as zinc, cobalt and nickel. New reactor systems are likely to be developed to increase the efficiency of bioleaching in terms of cost and kinetics. These innovations are expected to extend the scope of bleaching applications.

How is gold obtained from microbial leaching?

Gold is obtained through bioleaching of arsenopyrite/pyrite ore and its cyanidation process. Silver is more readily solubilized than gold during microbial leaching of iron sulphide.

What is leaching process?

Leaching process was first observed in pumps and pipelines installed in mine pits containing acid water. This process was later on employed for recovering metals from ores containing low quantity of the metal. Presently certain metals from sulfide ores and other ores are extracted by employing only leaching method.

How is copper produced?

Copper and Uranium are presently produced commercially by employing bioleaching process . However, problems may creep in when the large scale bioleaching process of a waste dump is improperly managed because seepage of leach fluids containing low pH and metals into natural water supplies and ground water causing metal pollution.

How do you extract copper from metal?

The extraction method used depends upon the metal’s position in the reactivity series . …

How is copper extracted from copper sulphate?

Copper can be extracted from non-sulfide ores by a different process involving three separate stages: Reaction of the ore (over quite a long time and on a huge scale) with a dilute acid such as dilute sulfuric acid to produce a very dilute copper (II) sulfate solution.

What kind of reaction is being used to extract copper from its salt solution using the iron nail?

After a displacement reaction, the less reactive element is now pure and left uncombined. In industry, we use iron to displace copper from solutions of waste copper compounds, which is really useful.

How is copper extracted from aqueous solution?

As the copper (II) aqueous solution was not stirred, the extraction occurs solely by diffusion processes. The color of the ionic liquid thick film adhered to the GC electrode was green-blue at the end of the experiment.

How can copper ions be extracted from the leachate to form pure copper?

The leachate contains the metal compound that we want to extract. The copper metal can be extracted by electrolysis or by a displacement reaction using iron. These methods allow for economical extraction of metals from the metal compounds.

How is copper extracted from copper rich ores?

Copper mining is usually performed using open-pit mining, in which a series of stepped benches are dug deeper and deeper into the earth over time. To remove the ore, boring machinery is used to drill holes into the hard rock, and explosives are inserted into the drill holes to blast and break the rock.

How do you manufacture copper?

This process involves drilling boreholes and pumping a leachate solution – usually sulfuric or hydrochloric acid – into the ore body. The leachate dissolves copper minerals before it is recovered via a second borehole. Further refining using SX-EW or chemical precipitation produces marketable copper cathodes.

How do select plants absorb copper compounds?

Select plants will absorb copper compounds through their roots, and the compounds become concentrated in the plant .

How is copper extracted from copper sulfate?

The copper is then extracted from the copper sulphate by displacement by scrap iron, or electrolysis.

What is the name of the solution of copper ions?

Bacteria feed on the low grade metal ores and form a solution of copper ions, called a leachate.

What is needed in the electrolysis step?

Energy is needed in the electrolysis step.

Can we use waste ores?

We can use waste ores, reducing the impact of mining on the environment.

What is the TCLP test?

The TCLP test was performed to evaluate whether the residual metals in the bioleached residue are soluble and migratory. And the results demonstrated that As, Cu, Mn and Ni were exceeded the limiting threshold ( Table 3 ). To be specific, it was noticed that potential toxic metals of As, Cu and Ni in the original CCES leachate were well above the limit regulatory of China for landfill disposal (Chinese National Standard, GB16889-2008). Furthermore, Cu, Mn and Ni of the raw material leachate are much higher than the limit of GB8978-1996. Suggesting that the untreated sludge had a high risk of environmental pollution. While after the bioleaching treatment in consortium, most of the mixed metals were removed and the bioleached residue passed the TCLP test successfully. Hence, the bioleached residue was well considered as non-hazardous waste and could be used as a raw material for the construction industry.

Is leached residue hazardous waste?

The leached residue would be considered as hazardous waste if the potentially toxic metals are still released into the environment. Therefore, the assessment of the leached residue depended on the Toxicity Characteristic Leaching Procedure (TCLP) test. At the end of experiments, the leached residues were washed 5 times with deionized water, and dried for the TCLP test. To be specific,1 g of dried residue was added to 20 mL of buffered acetic acid under the conditions of pH 4.93 ± 0.05, leaching for 18 ± 2 h with stirring speed of 30 ± 2 rpm and temperature at 23 ± 2 °C. Subsequently, leachate was collected and filtered for metals content determined by ICP-OES. The whole flow of the experimental process was shown in Fig. 2.

Is copper leaching faster than bioleaching?

Obviously, the yields from copper leaching in the sulfuric acid system were much lower than those from bioleaching. In fact, the rate of chemical leaching was faster than bioleaching in the first 4 days. This was due to the large proportion of Cu that existed in the sulfide state ( Fig. 1 ).

Is copper sludge recyclable?

Copper-Containing Electroplating Sludges is classified as hazardous waste. However, it can also be considered as recyclable resource as it contains a lot of valuable metals. Results show that bioleaching, using mixed microbes, has a much better performance (21.1% higher) than sulfuric acid leaching.

What is the process of breaking down low grade ores?

The solution is called a leachate and the process is called bioleaching.

How do plants absorb minerals?

Plants absorb mineral ions through their roots. Phytoextraction makes use of this to extract metals:

Which is more reactive, iron or copper?

Iron is more reactive than copper. It can displace copper from the leachate. For example:

How does mining for metals affect the environment?

Mining for metal ores involves quarries, which are large holes in the ground. These create noise, dust and traffic. They also destroy natural habitats. Phytoextraction reduces the need for mining, so reduces this damage.

How is copper recovered from PCBs?

About 100% copper was recovered in 2 h from 5 g/L PCBs by bacteria-free cultural supernatant. The result indicated that the indirect non-contact mechanism was the predominant mechanism in bioleaching of copper from PCBs. It was not necessary for bacteria to exist in copper extraction. In addition, the role of bacteria was most likely to regenerate Fe 3+ as an oxidant. Furthermore, the biooxidation of Fe 2+ to Fe 3+ was determined as the rate-limited step in bioleaching of copper from PCBs. In addition, the biooxidation activity of bacteria would be strongly inhibited by the toxicity of PCBs.

What are the two mechanisms of bioleaching?

The direct and indirect biooxidation are the two mechanism of bioleaching of ore. Usually, indirect biooxidation mechanism has been accepted by most researchers (Liu et al. 2017 ). The indirect biooxidation mechanism includes contact and non-contact biooxidation mechanisms (Jadhav and Hocheng 2013 ). In contact mechanism, bacteria would adhere to ore and form a biofilm between bacteria and ore. Inside this biofilm, Fe 2+ is oxidized by bacteria to Fe 3+ and the ore is dissolved by Fe 3+ (Liu et al. 2017 ). It has been proved that the formation of biofilm is important in bioleaching of ore (More et al. 2014 ). The concentration of ferric iron and H + in biofilm is much higher than that in solution, which could greatly increase the dissolution rate of ores (Coram and Rawlings 2002 ). In non-contact mechanism, the bacteria are no need to adhere to the ore. In addition, the Fe 3+ which is produced by bacteria plays key role in the dissolution of ore.

What is the toxicity of PCBs?

The toxicity of waste printed circuit boards (PCBs) to bacteria was considered as the major limitation in bioleaching of copper from PCBs. To reduce the toxicity of PCBs, copper extraction from PCBs was investigated using bacteria-free cultural supernatant from some metallurgical microbial consortium, whose predominant organisms were Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans.

How to reduce PCB toxicity?

2011 ), the use of adapted bacteria (Arshadi and Mousavi 2015 ), and the application of two-step process (Bryan et al. 2015 ). The two-step process was the most commonly used technology to reduce the toxic effect of PCBs (Isildar et al. 2016; Shah et al. 2015; Xiang et al. 2010 ). In the two-step process, bacteria were first cultivated for a period of time under its optimized conditions to obtain high activity; then, PCBs were added into the culture. The two-step process could improve the leaching efficiency and reduce the leaching time (Xiang et al. 2010; Zhu et al. 2011 ). As the bacteria in the two-step process had been cultured for a period of time without PCBs, there was high concentration of ferric ion in the solution before the addition of PCBs. This was consistent with the idea of using bacterial culture supernatant to leach PCBs in this paper. However, the oxidation activity of bacteria was inevitably affected after the addition of PCBs with the leaching efficiency reduced finally. Probably, the isolation of bacteria from the PCBs was the optimal way to avoid the toxicity of the PCBs. The results of this study also showed that the rate of copper extraction from PCBs increased significantly.

Which organisms were used to produce the supernatant?

A microbial consortium which Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans were the predominant organisms was used to produce the supernatant. The microbial consortium had been adapted in metal-contained medium for several years. In addition, the metal tolerance of the species in the literature and the microbial consortium used in this paper are shown in Table 2. It was indicated that the mixed culture used in this study had stronger metal tolerance.

How to immobilize bacteria?

For the purpose of immobilization of bacteria, pyrite was introduced into the process of bacterial oxidation of ferrous ions. Five grams pyrite was added into 90 mL adjusted 9K medium with 10% inoculum. The culture was cultivated at 42 °C and 180 rpm. After the ferrous ion in the solution was exhausted, the solution was stood and filtered to remove the supernatant. Then, 100 ml fresh adjusted 9K medium was injected into the precipitation for the bacterial culture. Once the ferrous ion was exhausted, the solution was stood, filtered. In addition, the fresh medium was injected again. Samples of bioleaching solution were collected to analyze pH, Eh, and the concentrations of Fe 2+ and Fe 3+. The experiments were conducted in triplicate.

Why are bacteria needed to form biofilm between bacteria and sulfide ore?

Therefore, bacteria were required to form biofilm between bacteria and sulfide ore to accelerate the dissolution of sulfide ores. While in bioleaching of PCBs, the copper was easily chemically leached by Fe 3+, and the addition of bacteria might not significantly increase the dissolution rate of copper.

Summary

See more on copper.org

Examples of Current Industrial Bioleaching Operations 1

Background

Chemistry of Bioleaching

Microbiology of Bioleaching

Leaching Method

Costs

Research

Conclusions