What is semi coke

News 2020-12-07

What is semi coke

Concept

Semi coke fired from high-quality Jurassic clean coal that is abundant in Shenfu coalfield. As a new type of carbon material, it has high fixed carbon, high specific resistance, high chemical activity, low ash content, low aluminum, low sulfur and low phosphorus have gradually replaced metallurgical coke and have been widely used in the production of calcium carbide, ferroalloy, ferrosilicon, silicon carbide and other products, becoming an irreplaceable carbon material. Semi coke can replace coke (metallurgical coke) and is widely used in chemical, smelting, gas production and other industries.Semi coke has a lump structure, generally between 0-80mm in particle size, and light black in color. There are two main specifications of Semi coke: one is domestic coke and the other is machine-made semi coke. Although the two specifications of semi coke are made from the same high-quality refined coal, their cost and quality are quite different due to different production processes and equipment. Among them, high-quality semi coke is mainly produced in Shenmu and Fugu in Shanxi

Raw materials

Generally, the raw materials of coke products are mainly coking coal, such as coking coal and fat coal, which have strong cohesive properties. Semi coke is generally produced from a single coal, and no coal blending is required in the production process.

Quality

Compared with common coke products, semi coke is a rare new type of clean energy. It has high fixed carbon, high specific resistance, high chemical activity, low ash ingredient, low aluminum, low sulfur, and low phosphorus, but at the same time the strength and crush resistance of semi coke are relatively poor. However, due to the discovery and exploitation of some high-quality coal resources in recent years, the semi coke produced from this raw material has a certain degree of bonding. These factors make the semi coke, which has low strength and poor crush resistance, have the mechanical properties of coke in a certain sense. The semi coke produced by some coking companies that use this as raw material also has the advantages of “four highs and four lows”. Such manufacturers are represented by a very small number of manufacturers in Xinjiang Guoxin, China. The main reason is that they are restricted by raw materials.

Application

Generally speaking, coke products are mostly used in metallurgical industries such as blast furnace iron-making and foundry. However, due to relatively poor strength and crush resistance, semi coke cannot be used in blast furnace production. However, in ferroalloy, calcium carbide, fertilizer and other industries, it can completely replace general coke, and its quality is better than many national standards for metallurgical coke, foundry coke and ferroalloy special coke. Therefore, semi coke is improving the quality of downstream products, saving energy.It has higher application value in terms of reducing production costs and increasing output. At the same time, semi coke also has development potential in the fields of blast furnace injection, production of carbonized materials, and activated carbon.

Technology

Generally, the technical production of coke products is mainly based on high-temperature dry distillation, and the dry distillation temperature usually needs to reach about 1000°C. After years of development, the equipment and technology of large-scale coke ovens are relatively mature and have the conditions to increase the unit output of equipment to achieve volume production. After entering the 21st century, the newly-built coke ovens will have an output of about 500,000 tons per year, and the highest can even exceed 1 million tons per year. For example, the two coking chambers of the Coking International Coking Plant that have recently been put into operation are 7.63 meters high. , The output can reach 1.1 million tons per year.

The production of semi coke is mostly based on low-temperature dry distillation, and the dry distillation temperature is generally around 600 ℃. Due to the late start, the annual output of a single furnace of semi coke low-temperature dry distillation equipment is mostly around 30,000 tons/year, and 50,000 tons/year. The forum low-temperature dry distillation furnace equipment of the above scale is still in the exploration and test stage. The technical process of large-scale equipment is still immature, and only one furnace and multiple doors and other combined technologies can be used to achieve centralized large-scale production.

Market prices

Due to differences in raw materials and processes, the market price of semi coke is much lower than that of ordinary coke. Taking 2006 as an example, the market price of semi coke was around 300 yuan/ton, and the average price of the lowest grade coke (10-25mm) was also around 760 yuan/ton. The relatively low market price makes semi coke products have higher market competitiveness.

Classification

Soil smelting

At the end of the 1970s, due to the constraints of traffic, transportation, and investment funds at that time, coal mines piled up the hard-to-sell lump coal on the flat ground, ignited it with an open flame, and then extinguished it with water to make semi coke. The process is simple and backward, but because of the good quality of coal, its products are still recognized by the majority of users, and it has become an irreplaceable high-quality carbon material in the production of calcium carbide and ferroalloy. This kind of local smelted semi coke is called : “soil smelted semi coke”.

Due to its simple and backward production process, and manual operation can only rely on experience to extinguish the fire, the quality cannot be stable. Under normal circumstances, the fixed carbon can only be guaranteed at about 82%, but because of its simple production process, investment The production cost is low, and the sales price is relatively low. However, because of its waste of resources and pollution of the environment, it has gradually stopped production at the beginning of this century.

Machine-made semi coke

In the 1990s, environmental management, pollution reduction, energy saving and consumption reduction have become people’s consensus. The state has issued a series of laws and regulations in this regard. Therefore, the use of mechanized furnace production technology to produce semi coke has been adopted by the local government. When it comes to the agenda, it has been accepted by most producers and has gradually taken shape.

As a result of the advanced dry distillation and burning process, the fixed charcoal is 5-10% higher than the soil refining charcoal, and the ash and V.M are reduced by 3-5%. Because the furnace is equipped with controllable temperature measuring equipment, the quality is relatively stable, using recycled gas to burn and dry the produced semi coke, which reduces the moisture ingredient, and the mechanical strength is also significantly higher than that of the local refining semi coke. Because mechanical operation is used instead of manual operation, such semi coke is called “machined blue charcoal”.