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Semi Coke

semi cokeSemi coke is also known as low temperature coke. Gray-black, volatile matter (about 7%-12%) is higher than that of coke (about 3%), the texture is crisp and porous, the reaction performance is good, it is easy to burn, and it is smokeless. The solid product of coal dry distillation at low temperature (500~600℃). It is used to make producer gas and water gas, and can also be used as fuel.

Semi coke is a new type of carbon material made from high-grade Jurassic coal.

Semi coke is light black, with high fixed carbon, high resistivity, high chemical activity, low ash, low sulfur and low phosphorus.

Characteristic

  • Semi-coke is black to dark gray in appearance, matt, soft and brittle, with open pores, its strength is worse than that of high-temperature coke, and its apparent density and true density are also lower than that of high-temperature coke.
  • The volatile content of semi-coke varies with the final temperature of dry distillation, generally 10-20%. Semi coke is easy to catch fire and has high reactivity. Semi-coke reactivity is generally determined by the critical air blast method. The smaller the measured value, the greater the reactivity. The critical air blast volume value of semi-coke averages 0.017L/min, while that of high-temperature coke can reach 0.057L/min.
  • The high volatile content of semi-coke increases the reactivity and decreases the ignition temperature. Semi-coke has a larger specific surface area, and some of its adsorption performance can be close to activated carbon or carbon molecular sieve. The properties of semi-coke depend on the properties of raw coal, dry distillation equipment and dry distillation process, mainly the dry distillation temperature and time.

Production process and equipment

There are many types of semi-coke production equipment. Dry distillation equipment can be divided into two categories: external heating and internal heating.

External heating type dry distillation equipment is to pack the coal in a ceramic or metal kiln and heat it from the outside. Due to the poor thermal conductivity of coal, in order to improve heat transfer, methods such as stirring, rotation, and multi-layer heating are also used, and the mechanism is relatively complicated. Internal heating type dry distillation equipment uses gas heat carrier or solid heat carrier to directly contact with coal for heating. The coal is rapidly heated by the heat carrier in a moving bed, fluidized bed or carrier bed and dry distilled into semi-coke.

There are four representative semi-coke production processes:

  1. Lurgi-Spier process. It was developed by Germany before the Second World War. The lump non-caking coal or briquette is dry distilled into semi-coke by the hot exhaust gas from top to bottom in the vertical internal heating furnace, and the semi-coke at the bottom of the furnace is quenched with cold coal gas and then discharged.
  2. Disco craftsmanship. Proposed by the United States in 1930. The weakly caking coal is heated in a continuous rotary kiln, and is discharged in the form of lump semi-coke after being bonded and carbonized.
  3. COED process. Developed by the United States in 1962. In this method, pulverized coal is retorted into semi-coke by heating gas and circulating hot semi-coke powder in four continuous fluidized beds.
    Ruchi-Ruhr process. In 1949, it was successfully studied by the
  4. Federal Republic of Germany. The pulverized coal uses the circulating hot semi-coke powder as the heat carrier. After being mixed with the circulating hot coke powder in the retort, the pulverized coal is quickly dry-distilled into semi-coke.

Semi Coke Specification Parameters

Size6-40mm(Various size ranges)
Fixed Carbon85% min
Moisture12% max
Sulphur0.40% max
Phosphorus0.020% max
Ash(Dry basis)0.020% max
Volatile Matter (dry basis)4.0% max
CSR18% max
CRI80% min
Reactivity(1100 C degree/%)96%
Reactivity(1100 C degree/%)3000-5000 degree/%Ω

Application

  • Semi coke powder can be used in blast furnace instead of coal injection in steel-making ;
  • 0-6mm semi coke can be used for sintering Mn ore in process of production SiMn; or using in other sinter mill.
  • 6-18mm semi coke can be used in producing Ferronickel , Ferrosilicon ,Calcium Carbide and other ferroalloys.
  • In industry, it is used in the fields of chemical industry, smelting, gas production, etc., and in civil use, it is used for heating and barbecue.
  • Application fields include clean fuel, coke field, metallurgy field, chemical industry field, adsorbent field.
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