The melting point of sulfur. Installations for melting sulfur

Sulfur is one of the most common elements of the earth's crust. Most often it is found in minerals that contain metals in addition to it. The processes occurring when the boiling point and melting point of sulfur are very interesting are very interesting. These processes, as well as the associated difficulties, we will discuss in this article. But first we will plunge into the history of the discovery of this element.

History

In its native form, as well as in the composition of minerals, sulfur has been known since antiquity. The old Greek texts describe the toxic effect of its compounds on the human body. Sulphurous gas, released by burning the compounds of this element, can indeed be deadly to humans. Around the 8th century, sulfur was used in China for the preparation of pyrotechnic mixtures. It's no wonder, because in this country, it is believed, invented gunpowder.

Even in ancient Egypt, people knew the method of burning sulfur-containing ore based on copper. Thus, this metal was mined. Sulfur was evacuated as a poison gas SO ₂ .

Despite the fame from ancient times, the knowledge of what constitutes sulfur came from the works of the French naturalist Antoine Lavoisier. He established that it is an element, and the products of its combustion are oxides.

Here is a brief history of dating people with this chemical element. Next, we will describe in detail the processes occurring in the bowels of the earth and leading to the formation of sulfur in the form in which it is now.

How does sulfur appear?

There is a common misconception that most often this element occurs in a native (that is, pure) form. However, this is not quite true. Native sulfur is most often found as an impregnation in another ore.

At the moment there are several theories concerning the origin of the element in its pure form. They assume a difference in the time of formation of sulfur and ores into which it interspersed. The first, the theory of syngenesis, presupposes the formation of sulfur together with ores. According to it, some bacteria living in the thickness of the ocean, restored sulphates, which are in the water, to hydrogen sulfide. The latter, in turn, rose upwards, where it was oxidized to sulfur with the help of other bacteria. She fell to the bottom, mixed with silt, and subsequently they formed ore together.

The essence of the theory of epigenesis is that sulfur in the ore was formed later than itself. There are several branches. We will only talk about the most common version of this theory. It consists in this: underground waters, flowing through accumulations of sulphate ores, are enriched by them. Then, passing through oil and gas fields, sulfate ions are reduced to hydrogen sulfide due to hydrocarbons. Sulfuric hydrogen, rising to the surface, is oxidized by air oxygen to sulfur, which settles in the rocks, forming crystals. This theory has recently found more and more evidence, but so far the question of the chemistry of these transformations remains open.

From the process of origin of sulfur in nature, we turn to its modifications.

Allotropy and polymorphism

Sulfur, like many other elements of the periodic table, exists in nature in several forms. In chemistry they are called allotropic modifications. There is a gray rhombic. Its melting point is somewhat lower than that of the second modification: monoclinic (112 and 119 degrees Celsius). And they differ in the structure of elementary cells. Rhombic sulfur is more dense and stable. It can be heated up to 95 degrees into a second form - monoclinic. The element we are discussing has analogues in the periodic table. Polymorphism of sulfur, selenium and tellurium has been discussed by scientists so far. They have a very close relationship with each other, and all the modifications that they form are very similar.

And then we will analyze the processes that occur during the melting of sulfur. But before you start, you should dip a little into the theory of the structure of the crystal lattice and the phenomena that occur during the phase transitions of matter.

What does the crystal consist of?

As is known, in a gaseous state the substance is in the form of molecules (or atoms) randomly moving in space. In a liquid substance, its constituent particles are grouped together, but they still have enough freedom of movement. In a solid state, everything is a little different. Here, the degree of ordering increases to its maximum value, and the atoms form a crystal lattice. In it, of course, oscillations occur, but they have a very small amplitude, and this can not be called a free movement.

Any crystal can be divided into elementary cells - such consecutive compounds of atoms, which are repeated throughout the sample of the compound. Here it is worthwhile to clarify that such cells are not a crystal lattice, and here the atoms are located inside the volume of a certain figure, and not at its nodes. For each crystal they are individual, but they can be divided into several basic types (syngonies) depending on geometry: triclinic, monoclinic, rhombic, rhombohedral, tetragonal, hexagonal, cubic.

Briefly analyze each type of lattice, because they are divided into several subspecies. And we will begin with what they can differ from each other. First, it is the ratio of the lengths of the sides, and secondly, the angle between them.

Thus, the triclinic syngony, the lowest of all, is an elementary lattice (parallelogram) in which all sides and angles are not equal. Another representative of the so-called lower category of syngonies is monoclinic. Here, the two cell angles are 90 degrees, and all sides have different lengths. The next species, belonging to the lowest category, is rhombic syngony. It has three unequal sides, but all the angles of the figure are equal to 90 degrees.

Let's move on to the middle category. And its first term is the tetragonal system. Here, by analogy, it is not difficult to guess that all the angles of the figure that it represents are equal to 90 degrees, and also two of the three sides are equal to each other. The next representative is a rhombohedral (trigonal) syngony. Here everything is a little more interesting. This type is determined by three identical sides and three angles, which are equal to each other, but are not straight.

The last variant of the middle category is hexagonal syngony. In its definition, even more complexity. This variant is built on three sides, two of which are equal and form an angle of 120 degrees, and the third is in the plane perpendicular to them. If we take three hexagonal cells and apply them to each other, we get a cylinder with a hexagonal base (that's why it has this name, because "hexa" in Latin means "six").

Well, the top of all syngonies, which has symmetry in all directions, is cubic. It is the only one belonging to the highest category. Here you can immediately guess how it can be characterized. All angles and sides are equal to each other and form a cube.

So, we have finished the analysis of the theory on the basic groups of syngonies, and now we will tell in more detail about the structure of various forms of sulfur and the properties that result from this.

The structure of sulfur

As already mentioned, sulfur has two modifications: rhombic and monoclinic. After the partition with the theory, it became clear what they are different for. But the whole point is that, depending on the temperature, the lattice structure can change. The whole point is in the process of transformations that take place when the melting point of sulfur is reached. Then the crystal lattice is completely destroyed, and the atoms can move more or less freely in space.

But let us return to the structure and features of such a substance as sulfur. The properties of chemical elements largely depend on their structure. For example, sulfur, due to its crystal structure, has the property of flotation. Its particles are not wetted by water, and the air bubbles sticking to them pull them to the surface. Thus, the gray sulfur emerges when immersed in water. This is the basis for some methods of separating this element from a mixture of the like. And then we will analyze the basic methods of mining this compound.

Extraction

Sulfur can lie with various minerals, and consequently, at different depths. Depending on this, different methods of extraction are chosen. If the depth is small and there are no accumulations of gases under the ground that interfere with the extraction, then the material is extracted in an open way: the rock layers are removed and, finding the ore containing sulfur, it is sent for processing. But if these conditions are not met and there are dangers, then the downhole method is used. It requires that the melting point of sulfur is reached. To do this, apply special settings. The apparatus for melting sulfuric acid in this method is simply necessary. But about this process, a little later.

In general, when mining sulfur in any way, there is a high risk of poisoning, because more often with it lie hydrogen sulphide and sulfur dioxide, which are very dangerous for humans.

In order to better understand what are the shortcomings and advantages of this or that method, we will get acquainted with the methods of processing sulfur-containing ore.

Extraction

Here, too, there are several techniques based on completely different properties of sulfur. Among them, thermal, extractive, steam-water, centrifugal and filtration ones are distinguished.

The most proven of them are thermal ones. They are based on the fact that the boiling point and melting point of sulfur is lower than that of the ores into which it "wedges". The only problem is that a lot of energy is consumed. To maintain the temperature, one had to burn some of the sulfur. Despite all simplicity, this method is ineffective, and losses can reach a record 45 percent.

We are going along a branch of historical development, so we turn to the steam-water method. Unlike thermal, these methods are still used in many factories. Strangely enough, they are based on the same property - the difference between the boiling point and the melting point of sulfur from similar parameters for the accompanying metals. The only difference is how the heating occurs. The whole process is in autoclaves - special installations. There is enriched sulfuric ore, containing up to 80% of the extracted element. Then, under pressure, hot water vapor is pumped into the autoclave. Warming up to 130 degrees Celsius, sulfur is melted and removed from the system. Of course, there are also so-called tails - particles of sulfur floating in the water, formed due to the condensation of water vapor. They are removed and put back into the process, since there too is a lot of the element we need.

One of the most modern methods is centrifugal. By the way, he developed in Russia. Briefly, its essence is that the melt of a mixture of sulfur and minerals, which it accompanies, is immersed in a centrifuge and unwinds at a high speed. The heavier rock, due to the centrifugal force, tends from the center, while the sulfur itself remains higher. Then the obtained layers are simply separated from each other.

There is another method, which is also still used in production. It is in the separation of sulfur from minerals through special filters.

In this article, we will only consider the thermal methods of extracting an element that is undoubtedly important for us.

The melting process

The study of heat transfer during the melting of sulfur is an important issue, because this is one of the most economical ways to extract this element. We can combine the parameters of the system with heating, and we need to calculate their optimal combination. It is for this purpose that the study of heat exchange and analysis of the features of the sulfur melting process is carried out. There are several types of installations for this process. A boiler for melting sulfur is one of them. Getting the item you are looking for with this product is just an auxiliary method. However, today there is a special installation - an apparatus for melting lump sulfur. It can be used efficiently in production to produce high purity sulfur in a large volume.

For the above purpose, in 1890 an installation was invented that allows the sulfur to be melted at a depth and pumped to the surface by a pipe. Its design is simple enough and effective in action: two pipes are in each other. The steam circulates overheated to 120 degrees (the melting point of sulfur) through the outer tube. The end of the inner tube reaches the deposits of the element we need. When heated by water, sulfur begins to melt and come out. Everything is simple enough. In the modern version, the installation contains another pipe: it is inside a pipe with sulfur, and compressed air passes through it, which causes the melt to rise faster.

There are several other methods, and in one of them the melting point of sulfur is reached. Under the ground, two electrodes are lowered and currents are discharged through them. Since sulfur is a typical dielectric, it does not conduct current and begins to heat up strongly. Thus, it melts and, with the help of a pipe, as in the first method, is pumped out. If sulfur is to be sent to the production of sulfuric acid, then it is ignited underground and the gas is discharged to the outside. It is oxidized to sulfur oxide (VI), and then dissolved in water to give the final product.

We have analyzed the melting of sulfur, the melting point of sulfur and the methods of its extraction. Now it's time to find out why such complicated methods are needed. In fact, the analysis of the melting process of sulfur and the temperature control system are necessary in order to clean and effectively use the final product of the extraction. After all, sulfur is one of the most important elements that play a key role in many spheres of our life.

Application

It is meaningless to say where sulfur compounds are used . It's easier to say where they do not apply. Sulfur is in any rubber and rubber products, in gas, which is fed to homes (there it is needed to identify the leak in the case of such). These are the most common and simple examples. In fact, the spheres of sulfur application are countless. To list them all is simply unrealistic. But if we undertake to do this, it turns out that sulfur is one of the most essential elements for humanity.

Conclusion

From this article you learned what the melting point of sulfur is, what this element is so important for us. If you are interested in this process and its study, then surely you have learned something new for yourself. For example, it may be features of melting sulfur. In any case, there is no limit to perfection, and none of us will be prevented from knowing the processes taking place in industry. You can independently continue to master the technological subtleties of the extraction, recovery and processing of sulfur and other elements contained in the earth's crust.