Recycling of Dedusting Ash from Steel Plant


Air-dried binder resisting CaO for pellet of Dedusting Ash

Dedusting ash generally refers to the dust, smoke, sludge and other wastes left by the dedusting of steel plant. For example, during the blast furnace and converter smelting process, there are blast furnace bag ash, ash collected by LT dedusting method, steelmaking dedusting ash, etc. Dedusting ash is rich in Fe, CaO, MgO, C, etc., and some also contain elements such as Zn, K, Na, etc., which has high recycling value, and direct disposal will easily cause resource waste and environmental pollution. At present, dust from steel plant is returned to the furnace for recycling, and cold-pressed pellets are often used for recycling.


Zn-rich ash contains a lot of environmental pollutants, which will not only cover a large area and cause environmental pollution problems, but also directly return to sinter production will also cause a decline in the quality of sinter, affecting the smooth running of the blast furnace and the life of the blast furnace. Therefore, in order to make reasonable use of this kind of dedusting ash, the dedusting ash can be mixed with a certain proportion of coke to make pellets, which can be molded with a binder and put into a rotary hearth furnace for direct reduction to form metallized pellets to remove harmful impurities, then put the pellets into the blast furnace for use. First, add reducing agent (coke, etc.), dust-removing ash binder, etc. to the dedusting ash, add water to make pellets, and dry them in a dryer (for customers who do not want to use drying equipment, we also have dedusting without drying Gray binder), resulting in green pellets with a certain strength, the moisture content of which is reduced to below 1, and then the dried green pellets are evenly arranged in the rotary hearth furnace through a vibrating distribution machine, and the temperature in the rotary hearth furnace is controlled at about 1250°C, the pellets are directly reduced in the furnace to produce metallized pellets that can be put into the blast furnace.

In order to recycle iron resources, binders can also be used to form pellets by cold pressing, but when alkaline oxides such as CaO and MgO cannot be digested or are not completely digested, the residual rate of alkaline oxides in dust will increase, while CaO , MgO, an alkaline oxide that meets water, dissolves and expands to 1.5 to 2.5 times its original volume, which will lead to cracking, disintegration, and even pulverization of the prepared pellets. Therefore, ordinary steel pelletizing binder cannot be used for dust removal and pressing balls, and must have anti-calcium components so that the pellets will not crack or pulverize during placement. At present, there are more and more anti-calcium binder on the market, but most of them add ammonia water and ammonia salt to solve the problem of calcium oxide. However, ammonia water and ammonia salt have a pungent smell, which is not conducive to production and workers' health.

In response to this situation, Air-dried Binder Resisting CaO for Pellet of Dedusting Ash series products can be use in the dust-free ash that has not been digested, incompletely digested or completely digested with calcium oxide, without drying process, save space and time, reduce production costs.

Post time: Apr-23-2023