1. Brief introduction
Modern blast furnace smelting need coke, its role in the blast furnace smelting process is to provide the heat; reduce the reducer that the iron ore need; and to hold the the permeability skeleton of the blast furnace (especially the soft melting part and the its below part). Blast furnace coal powder is mixed pulverized coal into the furnace from the blast furnace tuyere direct blowing pulverized the anthracite or bituminous coal powder or both, providing heat and reducing agent role to replace the coke, thereby reducing coke, reduces the cost of the iron, it is an important technical revolution of modern blast furnace smelting. 
2. Important meaning
Blast furnace coal injection is a revolutionary major measures for furnace iron-making technique. It is a key technology for the competitive with other ironmaking methods, the survival and development, and its significance for specific performance are as follows:
(1) Use the low price coal powder to replace the expensive and increasingly scare metallurgical coke, decreased the blast furnace ironmaking coke ratio, dropped the cost of pig iron.
(2) Coal injection is an effective means to adjust the furnace heat system.
(3) Coal injection can improve the working status of the blast furnace, made the operation of the blast furnace stable.
(4) Coal powder that injected gasification combustion before the tuyere can reduce the theoretical combustion temperature, so it need compensation in order to support power for the blast furnace melting, this created conditions for the blast furnace use high blast temperature and rich oxygen blast.
(5) In the process of injection coal powder released more hydrongen than coke, this improved the reducing capacity and penetration and diffusion ability of gas.
(6) Coal powder injection replaced part of metallurgical coke, not only ease the demand for coking coal, also reduced the coking facilities, can save the investment of infrastructure, especially need repaired coke oven which running time has reached 30 years, due to coal instead of coke decreased the demand of coke, coke oven should to overhaul can be shut down and abandoned.
(7) The coal powder injection instead of coke could reduce the number of the coke oven and the amount of the coke, so that could reduce the environment pollution in coking production. 
3. Process flow

3.1 Connected tanks injection
Below the coal bin equipped two groups of injection tanks (A, B tank), A and B injection tanks charging and waiting. By the materials in the weighing and detecting tank, when the material in the A tank reached the set lower limit then the B tank to inject, at the same time the A tank charging and waiting. 
The injection powder conveying pipe of the two groups connected to a main pipeline which reached to the blast furnace platform, and to inject before each blast furnace tuyere. 
3.2 String tanks injection

Below the coal powder bin equipped 1 set of rotary feeding device, it is the core equipment used for the metering, control and injection. I is constituted by upper and lower two string tanks, the upper tank is storage tank and the lower tank is injection tank, the injection tank continuously inject coal powder by rotary feeding pump under pressure, The inlet of the upper tank equipped with dome valve, in order to use flexible connection between the weighing metering valves of the lower tank. Below the injection tank equipped 1 rotary feed pump, the pump is driven by frequency conversion motor, to control the feeding quantity by adjusting the variable frequency motor speed, the coal powder is metered use volume by rotary feeding pump, and control by injection tank weighing system, discharging precision is 3%. The whole rotary feeding system can be achieved automatic control and operation through PLC. This injection way is accurate, stable. The feed valve of the equipment adopts dome valve, it is reliable sealing, wear prevention, improved the reliability of injection by using the inflation type of sealing structure.

I am in  Jinan City, Shandong Province