What is heap leaching copper?
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 heap leaching done?
In HL mined ore is crushed into small chunks, or ground and agglomerated into quasi-uniform particles, and heaped on an impermeable plastic and/or clay lined leach pad where it is irrigated with a leach solution which contains an appropriate leaching agent.
What are the four types of leaching?
There are four types of leaching:
- Cyanide leaching (e.g. gold ore)
- Ammonia leaching (e.g. crushed ore)
- Alkali leaching (e.g. bauxite ore)
- Acid leaching (e.g. sulfide ore)
How do you leach copper?
The most common reagent used in leaching of metals is sulphuric acid (H2SO4) [2]. Whereas other heavy metals are able to dissolve in H2SO4, copper (Cu) dissolves quicker in this acid than metals such as zinc, cobalt and iron because it is higher up in the electrochemical series.
What is meant by heap leaching?
Definition of heap leaching : a mining process in which metals are leached from a pile of crushed ore by a percolating solution (as of sodium cyanide)
What chemicals are used in heap leaching?
Lixiviants are chemical solutions used in leach mining to enhance dissolution of metals in ores. Sulphuric acid and cyanide salts are the most common demonstrated lixiviants used in heap or vat (tank) leaching processes applied under atmospheric conditions.
Which method is used for leaching?
In the leaching method, the ore is treated with a suitable reagent in which ore is soluble but impurities do not. Thus, impurities are removed by filtration. Among galena (PbS), copper pyrites (CuFeS2), cinnabar (HgS) and argentite (Ag2S) argentite being silver ore is concentrated by chemical leaching method.
Is heap leaching bad for the environment?
Release of toxic heap leaching fluids into the environment can affect the health of both the surrounding ecosystem and human population (Reichardt, 2008).
When did heap leaching begin?
Large-scale heap leaching can be said to have started in 1980 when three major copper projects were commissioned in Chile, and, at approximately the same time, a large number of gold projects were commissioned in the United States.
Which copper mineral would be most profitable to mine for copper?
Chalcocite
Chalcocite has been mined for centuries, and is one of the most profitable copper ores. The reason for that is its high copper content and the ease at which the copper it contains can be separated from sulfur.
When was copper leaching invented?
The first modern copper heap leach operation may have been the Bluebird copper oxide mine in 1968, followed in the early 1970s by other small operations in the United States.
How is copper ore leached?
The leaching reagent (dilute sulfuric acid) is sprayed through sprinklers on top of the heap pile and allowed to trickle down through the heap, where it dissolves the copper from the ore. The resulting “pregnant” leach solution of sulfuric acid and copper sulfate is collected in a small pool.
What is the principle of leaching?
Leaching is the process of extracting minerals from a solid by dissolving them in a liquid(not always a solvent). The soluble particles dissolve in to the liquid leaving back insoluble particles which may be seperated comfortably.
How do you extract copper from rocks?
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.
Why is heap leaching bad?
As the leachate travels through the layers of soil and rock, it can settle into the water table and spread much farther than expected from this pattern. This can lead to groundwater contamination that affects human health, livestock, or crops irrigated with the water.
Which method is commonly used to extract copper?
Copper is purified by electrolysis. In this process copper is transferred from an impure anode to the cathode of an electrolytic cell. The insoluble impurities fall to the bottom. The copper produced by this process is 99.99% pure copper.
What is heap leaching in copper?
Heap leaching consists of trickling H2SO4-containing lixiviant uniformly through flat-surfaced heaps of crushed ore, agglomerated, or run-of-mine ore. Heap leaching generates a pregnant leach solution (PLS) containing 1–6 g/L Cu²⁺, which is sent to solvent extraction and electrowinning for copper production.
Can this method be used to optimize heap leaching?
This method was applied to the extraction of copper from systems with one, two and three heaps, and the effects of copper price, ore grade and other variables were analyzed for each system. From the results, it can be concluded that this methodology can be used to optimize heap leaching processes, including planning and design issues.
How long does it take to leach copper ore?
The leaching cycle on a lift of fresh ore is to be 60 to 90 days – the exact cutoff to be determined according to the acid and copper in the off-solution. Acid application during the leaching cycle is keyed to the acid content of the off-solution – the higher the acid coming off, the lower the acid applied.
When was the first heap leach installed?
Gold and silver heap leaching began with the first Cortez heap leach in 1969. While many projects have come and gone, Cortez is still going – their new 63,000 tonne/day South Area leach is scheduled to start up in 2002.