Mercury is an extremely important metal that is used in almost all industrial sectors. Therefore, many countries are rapidly developing mercury industry and expanding the search for its deposits. What is the use of mercury in modern industry? Let’s try to understand this article.
What is mercury?
It is a chemical element and the only metal that is in a liquid state at normal temperature. A fluid substance of gray color is what mercury looks like, the photo of which is given below.
Mercury can harden only at very low temperatures. Medieval alchemists could not achieve the hardening of this metal. And only in 1759 the Russian academicians M.V. Lomonosov and I.A. Brown managed to do this. The fact is that in that year there were severe frosts in Russia, and with the help of special mixtures, scientists lowered the temperature to -56º. Under such conditions, mercury froze and became like metal. After a long time, other alchemists discovered a superconducting effect in mercury when they lowered the temperature to -270 ° C.
Mercury in the history of mankind
Mercury has been known to man since ancient times. The first mention of it is found in records of the V century BC. e. A lot of mercury has been studied in India and China. The oldest Indian school of alchemy is known as the "rasayana" or "path of mercury." She was involved in the development of medicines and various drugs.
Ancient people found mercury in nature in the form of cinnabar. They used it as a red dye. The name "cinnabar" is associated with an ancient legend and translates as "dragon blood." This characteristic of mercury is associated with religious beliefs. At that time, people believed that it was the blood of a sacred creature - a dragon killed in the mountains. Therefore, mercury was considered a healing substance capable of treating patients. One such remedy was mercury ointment.
Ancient alchemists considered mercury to be the basis of all metals and their life force. They were convinced that gold could be obtained from mercury and sulfur. But after numerous experiments and experiments, it became clear that nothing would come of this idea. How many scientists died trying to discover the formula for creating gold. And these studies continued until the 30s of the XX century, until science began to develop rapidly. As a result of the use of radioactive decay, scientists obtained stable isotopes of gold from mercury, but there were very few of them. And the price of such a metal is very high.
How is mercury mined?
The main and almost the only industrial source of mercury is the cinnabar mineral. It consists of 86% mercury sulfide, the remaining components are impurities of other minerals. Usually, cinnabar has the appearance of solid secretions, rich in impurities, and outwardly resembles grains of irregular shape. Rarely formed crystals of rhombohedral, bipyramidal shape. Doubles are sometimes found.
Cinnabar metal mercury is obtained by heating in an open tube that provides contact with oxygen. During heating, small droplets of mercury flow down the cold walls. Usually ore bodies occur at shallow depths and are confined to quartzites, limestones, dolomites and schists. The largest mercury deposits in the world are in Spain, the USA, Yugoslavia, Slovenia, Tajikistan, and Kyrgyzstan. Large crystals of mercury ore are mined in southern China.
Key mercury properties
This mineral has unique properties that have made the use of mercury in modern industry an important element. Mercury is considered a toxic and dangerous metal. But its physical and chemical properties in many areas of human activity are indispensable.
Physical properties
Mercury refers to diamagnets, as it can form hard alloys with other metals and liquid compounds - amalgams. The solidification temperature of mercury is -38.83 ° C, and the metal boils at 356.73 ° C. It evaporates at room temperature. Another important characteristic of mercury is that it is diamagnetic. This means that it is impossible to collect liquid metal balls with an ordinary magnet.
Chemical properties
Like noble metals, mercury is stable in dry air. It interacts with acids, salts, non-metals. Mercury does not react with water, alkalis and non-oxidizing acids. At temperatures above 300 ° C, it reacts with oxygen to form mercuric oxide.
The use of mercury in modern industry
Back in the Middle Ages, liquid metal was actively used in medicine for amalgamation and the manufacture of various devices. Nowadays, it is impossible to find a sector of the national economy that does not use mercury. The properties and application of this mineral are described by scientists from around the world in numerous scientific works.
So, mercury is used in agriculture for seed dressing. In the chemical industry, it is used as a catalyst for the production of acetic aldehyde from acetylene . The use of mercury cathodes makes it possible to isolate sodium chloride and chlorine from sodium chloride.
Mercury is an indispensable component in the manufacture of paints for the underwater part of marine vessels. The fact is that microorganisms living in sea water attach to the bottoms of vessels and contribute to corrosion and wear of metal parts. The mercury in the paint, under the influence of sea chlorine, forms a mercuric chloride, which poisons harmful bacteria.
Mercury is used even in the manufacture of felt. The salts contained in it perfectly degrease the fluff. Safer substitutes that would give the same effect have not yet been found. Mercury also serves as a catalyst during organic synthesis during the tanning process of the skin.
As already mentioned, mercury has always been used in medicine. Nowadays, antiseptic and diuretic drugs are produced on its basis. A mercury ointment was prepared in ancient India, the recipe of which has been preserved to this day. Due to its ability to dissolve other metals (tin, silver), mercury is used to make dental fillings.
The use of mercury in industry is also associated with its ability to evaporate at room temperature. For example, for oil refining. So, evaporation of the metal helps to control the temperature of oil refining processes.
Mercury devices
Physico-chemical properties are the main reason for the use of mercury in various devices and machines. Metal vapors are used in mercury turbines. Such installations are especially advantageous when there is little water in the unit and the mechanism is cooled exclusively by air.
In electrical engineering, rectifiers with a liquid mercury cathode are used. They allow you to convert a three-phase electric current into direct current. Even for astronomical purposes, mercury devices are used - horizons. They have a special vessel with liquid metal, the surface of which serves as a mirror during space observations. Also, the use of mercury in modern industry is manifested in the production of various diffusion pumps, circuit breakers, and thermometers.
Many branches of medicine use mercury-quartz lamps that are irradiated with ultraviolet rays. Also an indispensable medical tool is the well-known thermometer for measuring body temperature.
How much is mercury: price in the global market
The price of mercury is formed on the same principle as for other metals. So, the cost of this mineral depends on the supply and purity of the proposed mercury. In the global market, the price of mercury has dropped significantly over the past six months. So, if its average price at the end of 2014 was 75 USD / kg, then in March 2015 it was 55 USD / kg. But it’s almost impossible to buy liquid metal freely, since mercury is a chemical hazard. Even disposal of spilled mercury requires a certain amount to be paid.
For products that contain mercury, their cost depends on the amount of metal used and other production costs. For example, a mercury thermometer is very cheap. The price in pharmacies ranges from 25 to 50 rubles.
Health Hazards of Mercury
Despite the widespread use of mercury in industry, it is considered a rather dangerous chemical. According to the criteria of harm to life and health, mercury belongs to the first hazard class. Usually, mercury enters the body by inhaling its vapors, which are odorless. It is mercury vapor that poses the greatest danger.
To cause severe poisoning and health problems, exposure to a small amount of the mineral is sufficient. During toxicity, the lungs, kidneys, immune, nervous, digestive systems, eyes and skin are most affected.
Depending on the causes and nature of the poisoning, there are mild, acute and chronic forms. Mild toxicity occurs with food poisoning. After accidents at chemical enterprises or as a result of a safety violation, an acute form of poisoning appears. In this case, the patient has a decrease in mental activity, exhaustion, convulsions, loss of vision, baldness and even complete paralysis may appear. In severe cases, acute poisoning can be fatal. Chronic poisoning develops as a result of constant contact with mercury and can occur for a long time after stopping work with it. People with this form of pathology have an increased risk of developing hypertension, tuberculosis and atherosclerosis. There are times when chronic toxicity causes mental disorders.
Pregnant women should be especially careful with mercury devices. Mercury vapors pose a great threat to the development of the fetus. If there are children in the house, it is better to replace conventional mercury thermometers with electronic ones.
Disposal of mercury-containing waste
The widespread use of mercury contributes to a high concentration of its vapors in the atmosphere of large cities. Nowadays, fluorescent lamps are used everywhere, which contain from 30 to 300 mg of liquid metal. And in some lamps it is several times larger. According to statistics, annually about 100 million of such lamps become unusable and require processing. Only a small part of them undergo special disposal, and the rest immediately go to a landfill, where, due to the destruction of the integrity of the glass, mercury enters the atmosphere.
In addition, mercury is used in the production of rechargeable batteries and batteries, which are generally not processed in any way. In this way, about 40 tons of mercury fall into the landfill during the year. This figure is very large, so the problem of disposal of mercury-containing items is very acute. The uncontrolled handling of mercury wastes, the irresponsible attitude towards devices containing this liquid metal, poses a threat to human health and life. Everyone knows what troubles an ordinary mercury thermometer can bring. The price of mismanagement can even cost a life.
Now governments of all countries are working on the issue of processing mercury-containing waste. To this end, special companies are being created that are engaged in the collection of unusable devices and mercury items. They divide them into components (socles, glass, metal) and process them. Blocks are formed from each type of waste, which are packed in special containers (cases, plastic bags, canisters) and delivered to the place of processing.