Frequently asked questions about slag mill

Time:2023-06-30

Can industrial solid waste such as slag, furnace slag, and steel slag be reused to turn waste into treasure? The answer is of course yes. Zhuoya Mining Machinery’s high-pressure mill can process these industrial wastes and realize the recycling of resources. Today, the editor mainly talks about the common problems of slag and slag mills.

1. What are the types of slag discharged from thermal power plants and what are their uses?

There are two types of slag discharged from power plants:

1. The fine particles collected by the dust collector are called fly ash.

2. The slag collected at the bottom of the boiler combustion chamber mainly contains silicon oxide, aluminum oxide and iron oxide, which are sent to the ash yard by the mortar pump through the pressure ash removal pipeline.

Second, the use of power plant slag:

1. The amount of waste slag produced in the smelting process is very large. For example, 1 ton of pig iron produces about 0.3 to 1 ton of blast furnace slag; 1 ton of anode copper produced from copper concentrate produces about 5 to 6 tons of smelting slag. The waste slag that does not return to the basic smelting process should be comprehensively utilized. The slag can be made into cast stone products; the water-quenched slag is used to produce cement, slag brick or can be blown into slag wool as thermal insulation and heat insulation materials. Slag can also replace sand and gravel as ballast. Blast furnace slag can also be used

Slag

Used as flux in copper smelting process or as raw material of mold slag when casting steel ingot. Steelmaking slag with high P2O5 content is used as agricultural phosphate fertilizer. Copper smelting water quenching slag can be used as spraying material for surface treatment. The slag discharged from factory boilers is often regarded as waste, which not only occupies the fields, but also pollutes the environment. Slag has been widely used in various fields of industrial and agricultural production in the world.

3. What is the reason for the decline in the production capacity of the power plant slag grinding machine?

1) The high moisture content of slag increases the heat consumption of pulverized coal;

2) The quality of pulverized coal is inferior, resulting in large ash content and serious blockage of the flue;

3) The position of the pulverized coal bunker is relatively low, causing the wind to enter the furnace directly from the pulverized coal bunker through the secondary fan during coal mining;

4) The inspection and maintenance of the screw conveyor, primary fan, and secondary fan were not timely, resulting in insufficient coal delivery and air delivery.

5) The impeller of the main fan of the slag mill is not repaired and replaced in time, and the wear is serious, resulting in insufficient air volume in the system, a decrease in the air volume in the mill, dense fine powder on the grinding table, increased vibration value of the vertical mill, and decreased output.

Solution:

1) Strengthen raw material management. The slag storage yard is required to be stacked in order to ensure that the water slag entering the plant is stacked for more than 3 days, and the water content is lower than 10% before entering the receiving pit.

2) Strengthen fuel management. Coal powder is used as the fuel of the slag mill system, and its grade directly affects the stability of the hot air system. Therefore, strengthen raw coal quality management and pulverized coal workshop equipment management to ensure that the volatile content of pulverized coal entering the plant is > 15%, the calorific value > 21000KJ/kg, the ash content is ≤ 25%, and the fixed carbon is ≮ 60%, so as to maximize the improvement of coal production capacity. powder burning rate.

After the slag pulverized coal is burned, a small part of ash enters the slag mill with the airflow, and mixed with the slag powder, most of it settles in the furnace of the hot blast stove or sticks to the inner wall of the outlet pipe of the hot blast stove. , The cross-sectional area of the ventilation pipe is reduced, causing the heat to not be transported to the slag vertical mill, so that the slag vertical mill has insufficient heat supply and is forced to stop. Therefore, we opened a small hole directly in front of the hot blast stove pipe, requiring each shift to be cleared every day, and the effect is better. As shown below:

3) Due to the large air flow and high air pressure, when the position of the pulverized coal bin is low, the high-pressure airflow carries the pulverized coal into the hot blast stove, forcing the hot blast stove to turn off. Therefore, we require that the pulverized coal warehouse must ensure a certain storage space, and the hot blast stove workers need to contact the pulverized coal driver at any time to increase the frequency of coal mining and reduce the air flow.

4) Replace the impeller of the main fan of the slag mill. Regularly and regularly inspect or replace the impeller parts of the main fan.

After the above measures are taken, after the slag vertical mill starts, the pressure difference between the inlet and outlet is stable at 3.8KPa, the vibration value is stable at 3mm/s, the temperature of the hot blast stove is 1250°C, the operating pressure is 70bar, and the operation of the slag mill is gradually becoming stable.