Practice of technical reform of iron powder re-election for steelmaking dust extraction and reduction
I. Introduction
Steelworks dusts containing iron production processes contains 15% to 25% metallic iron, when climbing nanoelectronics "Nine Five" key, independent development of a new production process, after the ball milling reselection ferrous iron metal dust and other impurities are separated, the successful production of more than 90% of MFe reduced with iron powder (later referred to as iron), mainly for titanium-reducing agent, in 2001 results in smelter Very good run.
Due to the expansion of the steel plant and the optimization of the process, the annual sludge volume increased by more than 10,000 tons and the grade of the sludge was greatly reduced. If the original production process was not met, the original process was technically modified according to the current situation. After the technical transformation, the processing capacity has been greatly improved, and all the indicators can meet the product quality requirements.
Second, the cause analysis
(1) Analysis of raw materials
The raw material for the production of iron powder is the dust collected by the wet dust collector in the process of converter steel making. It is an artificial mineral with extremely unstable physical and chemical properties, and is also contaminated by impurities such as tar during the smelting process. Product stability has a certain impact.
The physical properties of the dust raw material fluctuate with the change of the smelting conditions, and the overall particle size is fine, wherein the -38um particle size content accounts for about 30% to 35%, and the finer the particle size, the lower the metal iron grade. The presence of the fine fraction is easy to absorb moisture and agglomerate due to its large specific surface area and high surface energy. For the -38um grade material, due to its fine particle size, ordinary sorting equipment cannot effectively sort it, and the particle size is too fine and easily oxidized. In this way, a large amount of low-grade fine mud occupies the processing space of the sorting equipment, so that the processing capacity is reduced, and the sorting precision is also affected, and the sorting index is lowered.
In addition, due to the optimization of the oxygen blowing process of steelmaking and the increase of slag forming agent, the particle size and grade of the sludge are affected, the grade of the sludge is getting lower and lower, and the requirements for the sorting equipment are higher. The original process production will not meet the production requirements.
(2) The original process flow and existing defects
1, the original process
The original process flow is shown in Figure 1.
2. Defects in the original process
(1) The capacity of one shake selection process is not enough: the shaker is a rough selection equipment, and the sludge with an increase of 10,000 tons per year is rough-selected, and the processing capacity is insufficient.
(2) The tube mill does not adequately grind the slurry: the concentration of the tube mill is low, and the ball loading rate in the tube mill is not high. The type of steel ball is only one type of small steel ball. The grinding and stripping force is not enough, so that the oxide and the metal iron cannot be effectively separated.
(3) Tube mill electromechanical consumption: tube mill motor power is 37KW, 4 tube mills work for 20 hours every day, then 4 tube mills consume 2960 degrees.
(4) The second shake selection of the incoming material is low: the concentration of the slurry from the tube mill is relatively thin, and it has not been sorted directly into the shaker for secondary selection. The grade of the coarse concentrate is not high, resulting in the second section selection. The effect is not good, so the final product quality is not stable.
Third, the solution
The existing process is optimized for the problems existing in the existing production process.
(1) New process
New process after transformation (slightly)
(2) Reform measures
1. Change a shaker to a spiral chute.
2. A classifier was added after a shaker to concentrate a section of coarse concentrate.
3. The four tube mills are connected in parallel to two energy-saving ball mills in series, and the ball mill balls are matched according to requirements.
4. Add a magnetic separator after adding a new ball mill.
Fourth, improve the effect
After the transformation of the above measures, after changing a shaker to spiral, it effectively increased the processing capacity of a rough selection, which can process the existing raw materials and increase the output of iron powder. After a shaker, the classification is increased. The machine concentrates a section of coarse concentrate to ensure the concentration of the second-stage ball mill to make the second-stage grinding more complete. The four tube mills are connected in parallel to two energy-saving ball mills in series, saving electricity and increasing the number of The ratio of the steel ball ensures that the slurry is effectively ground, so that the oxide and the metal iron can be effectively separated; a magnetic separator is added in the second stage, and the input grade of the two-stage shaker is further improved, and the shaker is effectively controlled. The feed concentration and grade make the grade of the second-stage concentrate more stable and meet the requirements; after the transformation, the product quality is stable, thus achieving good economic benefits.
V. Conclusion
(1) After the technical transformation, the sludge treatment capacity is effectively increased, and the energy consumption is further reduced.
(2) After the technical reform, the output of iron powder was increased, and the market share was further increased to meet the expected requirements.
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