Study On The Experiment And Mechanism Of Boracic Complex Additive To The Sinter

With the developing of modern blast-furnace smelting technology's, the request agglomerate's various aspects performance must enhance correspondingly, specially the agglomerate intensity and the granularity uniformity are good, may enhance on blast furnace's permeability. Increases the chemical additive in the agglomerate to be possible to improve the agglomerate liquid phase the production and solidifying, suppresses the pulverization. The adding in the agglomerate including the boric acid and the calcium chloride can enhance the agglomerate performance effectively. Through a series of metallurgy performance, the agglutination performance and the mechanism research, the boric acid and the calcium chloride have been chosen as take the agglomerate chemical additive the principal constituent. The chemical additive of the boric acid and the calcium chloride improvement distinctly agglomerate metallurgy performance, enhance the agglomerate mineralization rate and the improvement agglomerate agglutination performance. The chemical additive of the boric acid and the calcium chloride not only improved the agglomerate quality, but also comprehensive utilized to contain the boron mineral simultaneously. This research mainly concentrates three aspects:the metallurgy performance, the strengthened metallurgy performance mechanism and the agglutination performance.1. Adding chemical additive of the boric acid and the calcium chloride in the agglomerate including improved the agglomerate low temperature reduction pulverization rate obviously, other main metallurgy performance not change or slightly improvement and simultaneously enhanced the agglomerate mineralization rate.Uses the existing agglutination craft, after adding the chemical additive, may obtain a metallurgy performance better agglomerate. After adding the boric acid and the calcium chloride, agglomerate low temperature reducibility, the high temperature reducibility, the softening point and melt the sector not to change softly, the rotor drum intensity increase, it will not have the adverse effect to the blast furnace production pig iron's quality. The boric acid has the tremendous influence to the agglomerate grain-size distribution, the grain-size distribution is more reasonable, the agglomerate mineralization rate were enhanced obviously, reduces returns to the quantity of mineral deposits. After the agglomerate adding the boric acid, the granularity smaller than the 10mm pellet were reduces. The return rate (smaller than the 5mm agglomerate pellet percentage) drop 3 percentage points in the best sample, opposite the blank sample, the return rate reduced 38%. Adding the chemical additive of the boric acid and the calcium chloride, agglomerate low temperature reduce pulverization rate target large scale improvement. When adding the chemical additive of the boric acid and the calcium chloride total density were more than above 0.5%, the RDI increases above 4 percentage points, most increased nearly 12 percentage points. Adding the boric acid and the calcium chloride chemical additive is advantageous to blast furnace's normal operation, raise the blast furnace pig iron production rate and reduces the coke ratio.2. The agglutination mechanism is complex, the free energy, particularly superficial free energy reduction is essence. Adding chemical additive of the boric acid in the agglomerate, boric acid by many way influence the agglutination, including: impediment or selectively the crystal transformation, forms the new species and the phase, the change has the liquid phase condition.The new species were produced by adding boric acid. XRD experiment indicated that has the new species CaB6 production. The chemical actions of boric acid, hard powdered ore and carbon in agglutination process influence the agglutination process. In the agglutination process, condition change of the liquid phase production may reduce the agglutination briquetting the percentage open area. The experiment indicated that the agglomerate percentage open area were decrease above 20% after adding the boric acid. 3. The chemical additive changed the carbon kindling point, and that will affect the agglutination process of the agglomerate. The different chemical additive to the graphite, the anthracite as well as the simulation industry agglomerate combustion condition's influence is different. The compound chemical additive has overcome the adverse effect which the sole chemical additive possibly creates, improved the agglomerate agglutination process.The potassium permanganate, the calcium chloride, the potassium bichromate, the lithium carbonate, the boric acid, the hydrochloric acid, the calcium carbonate and the magnesium carbonate as the chemical additive or its compound chemical additive influence the kindling point of the graphite, the anthracite as well as the hard powdered ore and the graphite and the anthracite. The potassium permanganate, the calcium chloride, the potassium permanganate and the calcium chloride may reduce the carbon kindling point obviously. The potassium bichromate, the lithium carbonate may reduce the carbon kindling point. The hydrochloric acid, the calcium carbonate and the magnesium carbonate enhanced the carbon kindling point. The carbon kindling point was raises by boric acid obviously. The chemical additive's catalytic mechanism mainly displays to the fixed carbon catalytic combustion, but to volatile matter combustion not obvious catalytic effect.