Despite the fact that artificially created materials are increasingly used in industry and everyday life, it is not yet possible to refuse the use of metals. They have a unique combination of properties, and alloys allow you to maximize their potential. In what areas is the production and use of metals?
Characteristic of a group of elements
Metals are understood as a set of inorganic chemicals with characteristic properties. They typically include the following:
- high thermal conductivity;
- ductility, relative ease of machining;
- relatively high melting point;
- good electrical conductivity;
- characteristic "metallic" luster;
- role of reducing agent in reactions;
- high density.
Of course, not all elements of this group have all these properties, for example, mercury is liquid at room temperature, gallium melts from the heat of human hands, and bismuth can hardly be called plastic. But in general, all these features can be traced in the totality of metals.
Internal classification
Metals are conditionally divided into several categories, each of which combines elements that are closest to each other in various parameters. The following groups are distinguished:
- alkaline - 6;
- alkaline earth - 4;
- transitional - 38;
- light - 7;
- semimetals - 7;
- lanthanides - 14+1;
- actinides - 14+1;
Out of groups there are two more: beryllium and magnesium. Thus, at the moment, out of all discovered elements, 94 scientists attribute to metals.
In addition, it is worth mentioning that there are other classifications. According to them, noble metals, platinum group metals, post-transition, refractory, ferrous and non-ferrous metals, etc. are considered separately. This approach makes sense only for certain purposes, so it is more convenient to use the generally accepted classification.
Receipt History
Humanity throughout its development has been closely associated with the processing and use of metals. In addition to being the most common elements, various products could be made from them only with the help of mechanical processing. Since there were no skills in working with ore, at first it was only about the use of nuggets. At first it was a soft metal, which gave its name to the copper age, which replaced the stone one. During this period, the cold forging method was developed. Smelting has become possible in some civilizations. Gradually, people mastered getting coloredmetals such as gold, silver, tin.
Later the Bronze Age replaced the copper age. It lasted about 20 millennia and became a turning point for mankind, since it was during this period that it became possible to obtain alloys. There is a gradual development of metallurgy, methods of obtaining metals are being improved. However, in the 13-12 centuries. BC e. the so-called bronze collapse occurred, which marked the beginning of the Iron Age. This was presumably due to the depletion of tin reserves. And lead and mercury, discovered at that time, could not become a replacement for bronze. So people had to develop the production of metals from ores.
The next period did not last long - less than a millennium, but left a bright mark on history. Despite the fact that iron was known much earlier, it was almost never used because of its shortcomings compared to bronze. In addition, the latter was much easier to obtain, while smelting the ore was more labor intensive. The fact is that native iron is quite rare, so it is not surprising that the abandonment of bronze has been so slow.
Meaning of metal extraction skills
Similar to how the human ancestor first made a tool by tying a sharp stone to a stick, the transition to a new material turned out to be just as grandiose. The main advantages of metal products were that they were easier to make and repairable. The stone does not have plasticity and malleability, so thatany weapons from it could only be made anew, they could not be repaired.
Thus, it was the transition to the use of metals that led to the further improvement of tools, the emergence of new household items, decorations, which were previously impossible to make. All this gave impetus to technological progress and laid the foundation for the development of metallurgy.
Modern methods
If in ancient times people were only familiar with obtaining metals from ores, or they could be content with nuggets, then at present there are other ways. They became possible thanks to the development of chemistry. Thus, two main directions appeared:
- Pyrometallurgy. It began its development earlier and is associated with the high temperatures required to process the material. Modern technology in this area also allows the use of plasma.
- Hydrometallurgy. This direction is engaged in the extraction of elements from ores, waste, concentrates, etc. using water and chemical reagents. For example, a method involving the production of metals by electrolysis is extremely common, and the carburizing method is also quite popular.
There is another interesting technology. Obtaining precious metals of high purity and with minimal losses became possible thanks to it. It's about refinement. This process is one of the types of refining, that is, the gradual separation of impurities. For example, in the case of gold, saturation of the melt with chlorine is used, and platinum is dissolved inmineral acids followed by isolation with reagents.
By the way, obtaining metals by electrolysis is most often used if smelting or recovery is not economically viable. This is exactly what happens with aluminum and sodium. There are also more innovative technologies that make it possible to obtain non-ferrous metals even from fairly poor ores without significant costs, but we will talk about this a little later.
About alloys
Most of the metals known in antiquity did not always meet some needs. Corrosion, insufficient hardness, brittleness, fragility, fragility - each element in its pure form has its drawbacks. Therefore, it became necessary to find new materials that combine the advantages of the known ones, that is, to find ways to obtain metal alloys. Today there are two main methods:
- Casting. The melt of mixed components is cooled and crystallized. It was this method that made it possible to obtain the first samples of alloys: bronze and brass.
- Pressing. The mixture of powders is subjected to high pressure and then sintered.
Further improvement
In recent decades, the most promising is the production of metals using biotechnology, primarily with the help of bacteria. It has already become possible to extract copper, nickel, zinc, gold, and uranium from sulfide raw materials. Scientists hope to connect microorganisms to processes such as leaching, oxidation, sorption and precipitation. In addition, it is extremely importantthe problem of deep wastewater treatment, for this, too, they are trying to find a solution that involves the participation of bacteria.
Application
Without metals and alloys, life in the form in which it is now known to mankind would be impossible. High-rise buildings, airplanes, utensils, mirrors, electrical appliances, cars and much more exist only thanks to the distant transition of people from stone to copper, bronze and iron.
Because of their exceptional electrical and thermal conductivity, metals are used in wires and cables for a wide variety of applications. Gold is used to make non-oxidizing contacts. Due to their strength and hardness, metals are widely used in construction and for a wide variety of structures. Another area of application is instrumental. For the manufacture of a working, for example, cutting part, hard alloys and special types of steel are often used. Finally, noble metals are highly valued as a material for jewelry. So there are plenty of applications.
Interesting about metals and alloys
The use of these elements is so widespread and has such a long history that it is not surprising that various curious situations arise. They and just a couple of interesting facts should be brought in the end:
- Before its widespread use, aluminum was highly valued. Cutlery, which Napoleon III used when receiving guests, was made from this material and was the subject ofpride of the monarch.
- The name platinum in Spanish means "silver". The element received such an unflattering name due to the relatively high melting point and, therefore, the impossibility of using it for a long time.
- Pure gold is soft and easily scratched with a fingernail. That is why it is alloyed with silver or copper to make jewelry.
- There are alloys with a curious property of thermoelasticity, that is, the shape memory effect. When deformed and then heated, they return to their original state.
