Sulfur is one of the most common elements of the earth's crust. Most often, it is found in the composition of minerals containing metals in addition to it. The processes that occur when the boiling point and melting point of sulfur are reached are very interesting. We will analyze these processes, as well as the difficulties associated with them, in this article. But first, let's dive 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. In ancient Greek texts, the poisonous effect of its compounds on the human body is described. The sulfur dioxide released during the combustion of compounds of this element can indeed be deadly to people. Around the 8th century, sulfur began to be used in China to make pyrotechnic mixtures. No wonder, because it is in this country that gunpowder is believed to have been invented.
Even in ancient Egypt, people knew a method of roasting sulfur-containing ore based on copper. This is how the metal was mined. Sulfur escaped in the form of poisonous gas SO2.
Despite being famous since ancient times, the knowledge of what sulfur is, came thanks to the work of the French naturalist AntoineLavoisier. It was he who established that it is an element, and its combustion products are oxides.
Here is such a brief history of people's acquaintance with this chemical element. Next, we will talk in detail about the processes taking place in the bowels of the earth and leading to the formation of sulfur in the form in which it is now.
How does sulfur come about?
There is a common misconception that this element is most often found in its native (that is, pure) form. However, this is not quite true. Native sulfur is most often found as an inclusion in other ore.
At the moment, there are several theories regarding the origin of the element in its purest form. They suggest a difference in the time of formation of sulfur and the ores in which it is interspersed. The first, the theory of syngenesis, assumes the formation of sulfur together with ores. According to her, some bacteria that live in the ocean, reduced the sulfates in the water to hydrogen sulfide. The latter, in turn, rose up, where, with the help of other bacteria, it was oxidized to sulfur. She fell to the bottom, mixed with silt, and subsequently they together formed ore.
The essence of the theory of epigenesis is that sulfur in the ore was formed later than itself. There are several branches here. We will only talk about the most common version of this theory. It consists of this: groundwater, flowing through accumulations of sulfate ores, is enriched with them. Then, passing through oil and gas fields, sulfate ions are reduced to hydrogen sulfide due to hydrocarbons. Hydrogen sulfide, rising to the surface, is oxidizedatmospheric oxygen to sulfur, which settles in the rocks, forming crystals. This theory has recently found more and more confirmations, but the question of the chemistry of these transformations remains open.
From the process of the origin of sulfur in nature, let's move on 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 rhombic sulfur. Its melting point is slightly 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, when heated to 95 degrees, go into a second form - monoclinic. The element we are discussing has analogues in the periodic table. The polymorphism of sulfur, selenium and tellurium is still being discussed by scientists. 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 plunge a little into the theory of the structure of the crystal lattice and the phenomena that occur during phase transitions of matter.
What is a crystal made of?
As you know, in the gaseous state, the substance is in the form of molecules (or atoms), randomly moving in space. in liquid matterits constituent particles are grouped, but still have a fairly large freedom of movement. In a solid state of aggregation, everything is a little different. Here the degree of order increases to its maximum value, and the atoms form a crystal lattice. Of course, oscillations occur in it, but they have a very small amplitude, and this cannot be called free movement.
Any crystal can be divided into elementary cells - such consecutive compounds of atoms that are repeated throughout the entire volume of the sample compound. Here it is worth clarifying 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 main types (syngony) depending on the geometry: triclinic, monoclinic, rhombic, rhombohedral, tetragonal, hexagonal, cubic.
Let's briefly analyze each type of lattices, because they are divided into several subspecies. And let's start with how they can differ from each other. Firstly, these are the ratios 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 to each other. Another representative of the so-called lower category of syngonies is monoclinic. Here, two corners of the cell are 90 degrees, and all sides have different lengths. The next type belonging to the lowest category is the rhombic syngony. It has three unequal sides, but all the angles of the figureare equal to 90 degrees.
Let's move on to the middle category. And its first member is the tetragonal syngony. Here, by analogy, it is easy to guess that all the angles of the figure it represents are equal to 90 degrees, and also two of the three sides are equal to each other. The next representative is the rhombohedral (trigonal) syngony. This is where things get a little more interesting. This type is defined by three equal sides and three angles that are equal but not straight.
The last variant of the middle category is the hexagonal syngony. There is even more difficulty in defining it. This option is built on three sides, two of which are equal and form an angle of 120 degrees, and the third is in a plane perpendicular to them. If we take three cells of the hexagonal syngony and attach them to each other, we will get a cylinder with a hexagonal base (that is why it has such a name, because "hexa" in Latin means "six").
Well, the top of all syngonies, having symmetry in all directions, is cubic. She 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 and form a cube.
So, we have finished the analysis of the theory on the main groups of syngonies, and now we will tell in more detail about the structure of various forms of sulfur and the properties that follow from this.
The structure of sulfur
As already mentioned, sulfur has two modifications: rhombic and monoclinic. After the section on theorySurely it became clear how they differ. But the whole point is that, depending on the temperature, the structure of the lattice can change. The whole point is in the very process of transformations that occur 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's get back 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 the peculiarities of the crystal structure, has the property of flotation. Its particles are not wetted by water, and air bubbles adhering to them pull them to the surface. Thus, lump sulfur floats when immersed in water. This is the basis for some methods of separating this element from a mixture of similar ones. And then we will analyze the main methods for extracting this compound.
Production
Sulfur can occur with different minerals, and therefore at different depths. Depending on this, different extraction methods are chosen. If the depth is small and there are no accumulations of gases underground that interfere with mining, then the material is mined by an open method: rock layers are removed and, finding ore containing sulfur, they are sent for processing. But if these conditions are not met and there are dangers, then the borehole method is used. It needs to reach the melting point of sulfur. For this, special installations are used. An apparatus for melting lump sulfur in this method is simply necessary. But about this process - a littlelater.
In general, when extracting sulfur in any way, there is a high risk of poisoning, because most often hydrogen sulfide and sulfur dioxide are deposited with it, which are very dangerous for humans.
To better understand the disadvantages and advantages of a particular method, let's get acquainted with the methods of processing sulfur-containing ore.
Extraction
Here, too, there are several tricks based on completely different properties of sulfur. Among them are thermal, extraction, steam-water, centrifugal and filtration.
The most proven of them are thermal. They are based on the fact that the boiling and melting points of sulfur are lower than those of the ores into which it "weds". The only problem is that it consumes a lot of energy. To maintain the temperature, it used to be necessary to burn part of the sulfur. Despite its simplicity, this method is ineffective, and losses can reach a record 45 percent.
We are following the branch of historical development, so we are moving on to the steam-water method. Unlike thermal methods, these methods are still used in many factories. Oddly enough, they are based on the same property - the difference in the boiling point and melting point of sulfur from those for associated metals. The only difference is how the heating takes place. The whole process takes place in autoclaves - special installations. Enriched sulfur ore containing up to 80% of the mined element is supplied there. Then, under pressure, hot water is pumped into the autoclave.steam. Warming up to 130 degrees Celsius, sulfur melts and is removed from the system. Of course, the so-called tails remain - 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 they also contain a lot of the element we need.
One of the most modern methods - centrifuge. By the way, it was developed in Russia. In short, its essence is that the melt of a mixture of sulfur and minerals with which it accompanies is immersed in a centrifuge and spins at high speed. The heavier rock tends away from the center due to centrifugal force, while the sulfur itself remains higher. Then the resulting layers are simply separated from each other.
There is another method that is also used in production to this day. It consists in separating sulfur from minerals through special filters.
In this article, we will consider exclusively thermal methods for extracting an element that is undoubtedly important for us.
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 during heating, and we need to calculate their optimal combination. It is for this purpose that a study of heat transfer and an analysis of the features of the sulfur melting process are carried out. There are several types of installations for this process. The sulfur melting boiler is one of them. Getting the item you're looking for with this product- just a helper. However, today there is a special installation - an apparatus for melting lump sulfur. It can be effectively used in production to produce high-purity sulfur in large quantities.
For the above purpose, in 1890, an installation was invented that allows sulfur to be melted at a depth and pumped to the surface using a pipe. Its design is quite simple and effective in action: two pipes are located in each other. Steam superheated to 120 degrees (melting point of sulfur) circulates through the outer pipe. The end of the inner pipe reaches the deposits of the element we need. When heated by water, sulfur begins to melt and come out. Everything is quite simple. In the modern version, the installation contains another pipe: it is inside the pipe with sulfur, and compressed air flows through it, which makes the melt rise faster.
There are several more methods, and one of them reaches the melting point of sulfur. Two electrodes are lowered underground and a current is passed through them. Since sulfur is a typical dielectric, it does not conduct current and starts to get very hot. Thus, it melts and with the help of a pipe, as in the first method, it is pumped out. If they want to send sulfur to the production of sulfuric acid, then it is set on fire underground and the resulting gas is taken out. It is further oxidized to sulfur oxide (VI), and then dissolved in water, obtaining the final product.
We have analyzed the melting of sulfur, the melting of sulfur and methods of its extraction. Now it's time to find out why such complex methods are needed. In fact, the analysis of the process of melting sulfur andtemperature control system is needed in order to clean well and effectively apply the final product of the extraction. After all, sulfur is one of the most important elements that play a key role in many areas of our life.
Application
It makes no sense to say where sulfur compounds are used. It's easier to say where they don't apply. Sulfur is found in any rubber and rubber products, in the gas that is supplied to homes (there it is needed to identify a leak if one occurs). These are the most common and simple examples. In fact, the applications of sulfur 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, why this element is so important to us. If you are interested in this process and its study, then you have probably learned something new for yourself. For example, these may be features of the melting of sulfur. In any case, there is no limit to perfection, and knowledge of the processes taking place in industry will not interfere with any of us. You can independently continue mastering the technological intricacies of the processes of extraction, extraction and processing of sulfur and other elements contained in the earth's crust.
