Leaching . It is a process in which a liquid solvent is contacted with a pulverized solid, causing the dissolution of one of the components of the solid.
Summary
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- 1 Definition
- 2 Natural Leaching
- 3 Chemical Chemical Leaching
- 4 Examples
- 5 Importance for Science
- 1 Chemistry
- 2 Ecology
- 3 Geology
- 4 Agriculture
- 5 Extractive Metallurgy
- 6 Bioleaching
- 7 Practical applications
- 6 Sources
Definition
The word leaching comes from the Latin : “Lixivia, -ae” feminine noun meaning lye. The Romans used this term to refer to the juices that distill the grapes before stepping on them, or the olives before grinding them.
At present, leaching is called the washing of a pulverized substance to extract the soluble parts. It is also called one of the ways to obtain gold , for them the leaching with cyanide to the gold ore is used to purify it. This produces great contamination where the procedure is done due to the poisoning produced by the components of cyanide and the large amount of water that is used.
The washing (leaching) procedure is done in giant pools, up to the size of several Olympic stadiums, and unfortunately, later these residues will pass to the water tables that are generally located in the high mountains , which is where the mines are. of gold.
Natural leaching
Leaching produces the displacement of soluble or dispersible substances ( clay , salts , iron , humus , etc.); and that is why it is characteristic of humid climates ( Pluvisilva , etc.). This causes the upper horizons of the soil to lose their nutritive compounds, carried away by the water ; become more acidic , as there are insoluble compounds ( Aluminum ); and sometimes, toxicity also occurs . Large amounts of fertilizers are also lost , as are nutritional compounds.
In very humid climates, natural vegetation (especially forest) serves as protection against leaching. When man destroys it, this process is accelerated considerably and the retention of nutrients in the root zone is interrupted (there are no roots). Other ways to contribute to leaching are through the use of fertilizers with high acidity, excessive irrigation and crops that retain many nutrients from the soil. This process is also associated with weathering phenomena
Another effect of this natural process occurs when certain concentrations of toxic substances and components found in the soil, when in prolonged contact with water, diffuse into the environment and attack it.
Chemical Mining Leaching
Leaching is a process in which one or more solutes are extracted from a solid, using a liquid solvent. Both phases come into intimate contact and the solute or solutes can diffuse from the solid to the liquid phase, resulting in a separation of the original components of the solid.
Examples
- The sugaris leached from the beets with hot water.
- Vegetable oils are recovered from seeds, such as soybeanand cottonseed, by leaching with organic solvents.
- The extraction of dyes is carried out from solid materials by leaching with alcoholor soda.
Importance for Sciences
Chemistry
Leaching is a process by which one or more olutos is extracted from a solid, using a liquid solvent. Both phases come into intimate contact and the solute or solutes can diffuse from the solid to the liquid phase, resulting in a separation of the original components of the solid. It is of great importance in the field of metallurgy since it is mainly used in the extraction of some minerals such as gold, silver and copper . It is also used in Pharmaceutical Technology.
Ecology
The term in ecology is also applicable to indicate the movement of waste and excrement to rivers and seas, in addition to other contaminants such as fertilizers; produced by the same process indicated for the chemical phenomenon. The phenomenon of nutrient displacement is considered, these being carried away by water, this in turn caused by anthropogenic deforestation (caused by man).
geology
In geological science, leaching is understood as the process of washing a soil layer or geological layer with water. As well as by acidic plates found in salts that dissolve almost any solid material.
farming
In irrigation systems, when this is done with waters with a significant saline content, a greater quantity of water is dosed than what is strictly necessary for the plants, so that, when this water leaks into the drains, it prevents the accumulation of salts in the field, which could be negative for plants. This additional amount of water is called leachate water. In the case of complementary irrigation, in areas where there is reasonable annual precipitation, the leaching process of agricultural soils occurs naturally in periods of precipitation .
Extractive Metallurgy
It is also the process used in metallurgy , to work mainly oxidized minerals. For some time now, the leaching of copper sulphide minerals has been carried out by means of bacterial leaching processes. In the case of the leaching of gold minerals ( oxides ) the design of the pads are according to the morphology of the area, according to this we will be starting the details for the selection of the type of Pad, whether it is a reusable pad, expandable or the valley type leaching case ( Pierina case ).
Bioleaching
It is the process in which leaching is assisted by microorganisms, which play the role of catalysts. The bioleaching is a technique used for the recovery of metals such as copper, silver and gold and others. This last application is also known as biohydrometallurgy .
Practical applications
Industrially, leaching is used to prepare potions , for this the drug (usually a medicinal plant) is taken, pulverized, and mixed with the menstruum (alcohol), placed in a leach and left to macerate for the required time. Leaching can also be said to the treatment of concentrated minerals and other metal-containing materials, leaching is done by means of a wet acid process that dissolves soluble minerals and recovers them in a charged leaching solution. Practical use in mining by cyanidating gold and other minerals.
