In the process selection of magnesium smelting, a new type of Pidgeon process with mature, reliable and reasonable technology is adopted. Including raw material storage, dolomite calcination, grinding and ball pressing, reduction and refining sections.
Raw material reserve
Dolomite is crushed to the required particle size in the mine and stored in the dolomite yard in the plant. Ferrosilicon and fluorite are directly stored in the factory warehouse. All reserves are considered based on the amount required for half a month's production.
Rotary kiln for Philippines
Dolomite calcination workshop
Energy saving and environmental protection rotary kiln with vertical preheater and vertical cooler is selected. The dolomite with external particle size and quality meeting the requirements shall be unloaded to the stock yard, stacked and taken by the loader, screened by the vibrating screen, and then transported by the belt to the silo at the top of the shaft preheater of the rotary kiln. The dolomite with particle size of 10-40mm enters the preheater through the material pipe and exchanges heat with the high temperature flue gas flowing from the rotary kiln. The material shall be preheated to above 800 ℃ and then dropped to the transfer chute before entering the rotary kiln The activated calcined white is calcined at 1250 ℃ and then discharged into the cooler. The high-temperature calcined white exchanges heat with the cold air blown in by the fan here. The activated calcined white is cooled to below 100 ℃, and the air is preheated to above 600 ℃. The cooled active calcined white is discharged by the cooler and then transported to the ball making workshop by the scale conveyor. DCS central control system with advanced technology and reliable performance is adopted for the whole line, and centralized operation and management are conducted in the main control room.
After heat exchange with dolomite in preheater, the high-temperature flue gas generated by rotary kiln combustion will be cooled to below 250 ~ 280 ℃, and then it will enter into bag type dust collector. After dust removal, it will be discharged into the atmosphere through high-temperature fan, and the dust concentration of the discharged gas is less than 30mg / m3.
Ball making workshop
The calcined dolomite is fed into 1 bin by the elevator for standby; the ferrosilicon is crushed to below 20mm by the jaw crusher, and then lifted into 2 ferrosilicon block bin by the elevator for standby; the fluorite powder is lifted into 3 bin by a single bucket. Three kinds of raw materials stored in the storage bin are added into the ball mill for mixing and grinding by the microcomputer controlled continuous batching. The particle size is required to be less than 100 mesh. After passing through the elevator, storage bin and buried scraper conveyor, the mixed powder enters the ball press and is made into the ball pellet. The intelligent control system is selected for the batching system, and the whole process is fully automated by computer monitoring. The ball mill is driven by 10kv High-voltage Motor, which reduces the power loss compared with the original 380V low-voltage distribution operation.
Rotary kiln for Shanxi province China
The ball making workshop is equipped with 3 sets of dedusting systems, C1 × dedusting system is set at the crushing place of ferrosilicon, C2 × dedusting system is set at the batching grinding place and C3 × dedusting system is set at the ball pressing place. After comprehensive dust control, the operation environment of the ball making workshop is greatly improved compared with the traditional workshop, and the working environment of the workers is improved.
Reduction and refining workshop
The reduction furnace adopts high temperature air rapid reversing regenerative combustion technology, and the regenerative reduction furnace uses gas as fuel for continuous heating. The pellet is added into the reduction tank in the reduction furnace by the feeder, and the magnesium vapor generated in the reduction tank is condensed into crystalline magnesium (crude magnesium) in the end condenser, and the crude magnesium is taken out and sent to the refining and alloy production line.
In order to improve the thermal efficiency of the furnace and reduce the fuel consumption per unit product, the following measures are taken in the engineering design:
1. Fuel burning equipment: select energy-saving burner, automatically control air distribution, reduce incomplete combustion loss of fuel.
2. A vertical preheater is set at the end of the rotary kiln to make full use of the high-temperature flue gas generated by the combustion of the rotary kiln to preheat the materials in the preheater, so that the materials are partially decomposed in the preheater, and the system output is increased by 40% and the thermal efficiency is increased by 30%.
3.A vertical cooler is arranged at the head of the rotary kiln to fully utilize the heat contained in the high-temperature calcined white discharge of the rotary kiln to preheat the secondary air to 600 ℃, so as to improve the thermal efficiency.