Despite the fact that artificially created materials are increasingly used in industry and everyday life, it is still not possible to abandon 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?
Feature Group Feature
By metals is meant a combination of inorganic chemicals with characteristic properties. Typically, they include the following:
- high thermal conductivity;
- ductility, relative ease of machining;
- relatively high melting point;
- good electrical conductivity;
- characteristic "metallic" shine;
- the role of the reducing agent in the reactions;
- high density.
Of course, not all elements of this group possess all these properties, for example, liquid mercury 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 aggregate of metals.
Internal classification
Metals are conventionally 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;
- lungs - 7;
- semimetals - 7;
- lanthanides - 14 + 1;
- actinides - 14 + 1;
Outside the groups, two more remain: beryllium and magnesium. Thus, at present, of all the open elements, 94 scientists attribute to metals.
In addition, it is worth mentioning that there are other classifications. According to them, the noble metals of the platinum group, post-transition, refractory, ferrous and non-ferrous, etc. are separately considered. 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. Besides the fact that they turned out to be 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 using nuggets. At first it was soft metal, which gave the name to the copper age, which replaced the stone. During this period, the cold forging method was developed. In some civilizations, smelting has become possible. Gradually, people mastered the production of non-ferrous metals, such as gold, silver, tin.
Later, the Bronze Age replaced the copper one. It lasted about 20 millennia and became a turning point for humanity, since it was during this period that it became possible to obtain alloys. There is a gradual development of metallurgy, improving methods for producing metals. However, in the 13-12 centuries. BC e. the so-called bronze collapse occurred, which marked the beginning of the Iron Age. This was allegedly due to depletion of tin. And the lead and mercury discovered at this time could not become a substitute 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 in history. Despite the fact that iron was known much earlier, it was hardly used because of its shortcomings compared to bronze. In addition, the latter was much easier to obtain, while smelting the ore was a more time-consuming task. The thing is that native iron is quite rare, so it is not surprising that the rejection of bronze was so slow.
The value of metal extraction skills
By analogy with how a human ancestor first made a tool, having tied 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 there was also the possibility of mending. The stone does not have plasticity and malleability, so that any tools 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, jewelry, which it was previously impossible to make. All this gave an 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 high temperatures necessary for processing the material. Modern technologies in this area also allow the use of plasma.
- Hydrometallurgy. This area 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 cementation method is also quite popular.
There is another interesting technology. The receipt of precious metals of high purity and with minimal losses became possible precisely thanks to it. It's about refining. This process is one of the types of refining, that is, the gradual separation of impurities. For example, in the case of gold, the melt is saturated with chlorine, and platinum is dissolved in mineral acids, followed by isolation with reagents.
By the way, the production of metals by electrolysis is most often used if smelting or reduction is economically disadvantageous. This is exactly what happens with aluminum and sodium. There are more innovative technologies that make it possible to obtain non-ferrous metals even from fairly poor ores without significant costs, but this will be discussed a little later.
About alloys
Most of the metals known in antiquity did not always meet certain needs. Corrosion, insufficient hardness, brittleness, brittleness, fragility - each element in its pure form has its drawbacks. Therefore, it became necessary to find new materials that combine the advantages of the well-known, that is, find methods for producing metal alloys. Today, there are two main methods:
- Casting. The melt of the mixed components is cooled and crystallized. It was this method that made it possible to obtain the first alloy samples: bronze and brass.
- Pressing. A mixture of powders is subjected to high pressure and then sintered.
Further improvement
In recent decades, the most promising way to get metals using biotechnology, primarily with 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, the problem of deep wastewater treatment is extremely urgent; they are also trying to find a solution for it involving bacteria.
Application
Without metals and alloys, life in the form in which it is now known to mankind would have been impossible. High-rise buildings, airplanes, dishes, mirrors, electrical appliances, automobiles and much more exist only due 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 purposes. Gold is used to make non-oxidizable 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, carbides and special types of steel are often used. Finally, noble metals are highly regarded as 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 curious facts should be brought to the end:
- Prior to its wide distribution, aluminum was very much appreciated. The cutlery used by Napoleon III at the reception was made of this material and was the pride of the monarch.
- The name platinum in translation from Spanish means "silver". The element received such an unflattering name due to the relatively high melting point and, therefore, the inability to use it for a long time.
- In its pure form, gold is soft and can easily be scratched with a fingernail. That is why for the manufacture of jewelry it is fused with silver or copper.
- There are alloys with a curious property of thermoelasticity, that is, the effect of "shape memory". Upon deformation and subsequent heating, they return to their original state.