CN1290731A - Adhesive for pelletizing and its producing method - Google Patents

Abstract

The adhesive of the present invention is used in pelletizing metallurgical dust. It consists of two inorganic adhesive components, A and B, in the ratio of 1-2. The component A consists of CaO 38-44 wt%, SO3 6-10 wt%, Al2O3 28-38 wt% and SiO2 less than 10 wt% other than Fe3O3 and impurity. The component B consists of CaO 40-52 wt% and SO3 28-44 wt% other than impurity. The adhesive in low in cost and high in pelletizing effect, may be used to simplify pelletizing process and be reused.

Description

Adhesive for granulating and its preparing process

The invention relates to a binder for granulation and a manufacturing method thereof, belongs to a binder for granulation of metallurgical dust waste and a manufacturing method thereof, and is particularly suitable for granulation of sintering dedusting ash.

The sintering dust removal ash is mainly derived from a large amount of dust accumulated by various dust removal facilities for crushing molten fuel, exhausting air of a sintering machine and sieving finished ore in the sintering production process, and accounts for about 2-2.5% of the output of the sintered ore. On one hand, the sintering dust removal ash has fine granularity and strong hydrophobicity, is difficult to process and treat, and is easy to flow and float along with wind, so that the environmental pollution is easily caused; on the other hand, the sintering dust removal ash contains higher beneficial components such as TFeO, CaO, MgO and the like, has higher utilization value, and can be used as a substitute of sintering raw materials and fuels. In the prior art, the recovered fly ash is mostly directly mixed into a sintering mixture in the utilization of sintering fly ash, and because the dust has extremely fine granularity, the dust is difficult to be uniformly mixed with the sintering mixture, so that the stability of components of a sintering ore is influenced; more seriously, the dust withextremely fine granularity and strong hydrophobicity is directly added into the mixture, so that the granulation effect of the mixture is reduced, the air permeability of a sinter bed is seriously influenced, and the sintering yield and the sintering effect are influenced; meanwhile, a large amount of generated dust enters the dust removal circulating system again to form vicious circulation and cause the pollution of secondary raised dust to the post operation environment. The Chinese patent application publication No. 94103910.2 discloses alkaline, carbon-containing, dust powder cold-bonded pellet, which uses cold-bonding process, wherein 86% of converter dust is used as main raw material, and 6% of carbon and 8% of water glass are added; it can also use 50% converter smoke, 10% electric furnace smoke, 10% iron powder as main raw material, and add 6% carbon, 7% water glass, 1% kaolin. During granulation, in order to achieve the strength required by subsequent production, the uniformly mixed raw materials are extruded into balls by a ball press machine, and the balls are dried for 25-30 minutes at the temperature of 250-300 ℃, so that the preparation process is complex and the cost is high. Moreover, water glass is expensive, which further increases the cost of granulation.

The invention aims to provide a granulating binder which has low cost, can simplify a granulating process, has good balling effect and can be recrystallized after being crushed, and a preparation method thereof.

The object of the invention is achieved by the following technical solution.

A binder for granulating comprises A, B inorganic binders, group AThe inorganic binder comprises the following chemical components in percentage by weight: 38-44% of CaO and SO₃6～10％、Al₂O₃28～38％、SiO₂Less than 10%, the balance being Fe₂O₃And other impurities; the component B comprises the following chemical components in percentage by weight: 40-52% of CaO and SO₃28-44% of the balance of other impurities; the ratio of the component A inorganic binder to the component B inorganic binder is 1: 0.5-1.

The method for manufacturing the binder for granulation comprises the following steps:

the component A comprises the following raw materials in percentage by weight: 40-55% of limestone, 30-40% of alundum and 15-25% of gypsum, firing the ingredients at 1300-1400 ℃ to form clinker, grinding the clinker together to obtain the product with the specific surface area of more than 380m²Kg, specific gravity of 2.7-3.0 g/cm³The component A is an inorganic binder;

the component B comprises the following raw materials in percentage by weight: 70-90% of anhydrite and 10-30% of lime, and grinding the ingredients together to prepare the gypsum with the specific surface area larger than 300m²Kg, specific gravity of 2.5-2.8 g/cm³The component B of (1) an inorganic binder.

The anhydrite in the ingredient of the component B can also be gypsum calcined at the temperature of 800-1000 ℃ for 20-30 minutes.

The main mineral in the component A inorganic binder is 3CaO 3Al₂O₃·CaSO₄The sulphoaluminate type inorganic compound can react with gypsum and lime in the material B at the optimal speed and effect in the presence of water to quickly generate ettringite which plays an inorganic gelling role. Component A inorganic binder and component B inorganic binderThe agent is mixed with the water-containing powder for 24 hours respectively without coagulation, and the agent and the water-containing powder can be solidified within 10-30 minutes after being fully mixed simultaneously. The two can form a strong skeleton in a short time in the presence of water, and simultaneously separate out aluminic acid, so that the proportion of crystals and gel in a hardened body is coordinated, and the internal stress is reduced. It represents the reaction formula: (1) (2)2CaO·SiO₂+nH₂O→C-Si-H+Ca(OH)₂

ca (OH) formed in the reaction₂Under the condition of alkaline and gypsum, the reaction can generate ettringite and promote C₂And (4) hydration reaction of S.

The hydration hardening reaction of the granulation binder can be shown simply as follows:

(Binder + H)₂O) hydration → gelling and curing → strength hardening

When the two components are fully mixed with water and are hydrated and dissolved to reach a saturation stage, various ions generate crystal particles due to supersaturation, and hydrates are gradually connected by dendritic crystals and colloidal ion groups. The close nature and particle size of the various minerals are a prerequisite for this reaction to occur, while sufficient water is a prerequisite for the reaction to proceed. The dedusting ash, the adhesive for granulation and water are mixed in proportion and then recombined into large micelles, the micelles are connected with each other, and the connected gaps are filled with water, namely gelatinization. According to the double-electric layer theory of the gelling chemistry, due to the action of electrostatic attraction, crystal branches near a micelle grow rapidly along with the development of gelling, and continuously absorb surrounding water molecules, and the water molecules are used as a component in hydrated crystals and fixed on the positions of the crystals.

Compared with the prior art, the invention has the advantages that: the raw materials of the binder for granulating are easy to obtain, the manufacturing process is simple, and the cost is low; the water-absorbing agent has strong water absorption, can bond water with the volume 9 times of the water-absorbing agent and other solid materials into a solid in a short time, and the weight-to-water-solid ratio can reach 2.5: 1; since the main reaction is hydration, it reflectsThe speed is high, the action time is short, the balling is rapid, and the pelletizing process is only 5-10 minutes; the bonded material has high strength, and the strength of the produced sintered dedusting ash green ball can reach 2 Kg/cm only by granulating through a pelletizing disc²The granulation process is simple, the balling effect is good, and the crushed green balls can be recrystallized. The sintering dedusting ash green ball produced by adopting the binder for granulation is mixed into the sintering mixture, so that the granulation effect and the granularity composition of the mixture are improved, the air permeability of a material layer is effectively improved, and the sintering process is improved. Meanwhile, the pollution of fine dust circulation and secondary dust raising to the post operation environment is greatly reduced, the environmental condition is obviously improved, and the environmental protection benefit is obvious. In addition, the inorganic binder of the component A and the inorganic binder of the component B are respectively mixed with the hydrous powder for 24 hours without coagulation, so the binder for granulation also has the advantage of convenient transportation and storage.

The present invention will be described in detail with reference to examples.

Example 1:

the component A comprises the following raw materials in percentage by weight: 40% of limestone, 40% of aluminumstone and 20% of gypsum. The ingredients are crushed in a crusher together until the granularity reaches 2-10 mm, then the ingredients are fired into clinker through a rotary kiln at the temperature of 1300 ℃, and the clinker is ground in a mill to prepare khaki fine powder, namely the component A inorganic binder, wherein the physicochemical properties of the component A are shown in the attached table.

The component B comprises the following raw materials in percentage by weight: 80% of anhydrite and 20% of lime. Grinding the ingredients in a mill to obtain grey white fine powder, namely the component B inorganic binder, wherein the physical and chemical properties of the component B inorganic binder are shown in the attached table.

Example 2

The component A comprises the following raw materials in percentage by weight: 55% of limestone, 30% of aluminum oxide and 15% of gypsum. The firing temperature was 1350 deg.C, and the other processes were the same as in example 1. The physical and chemical properties of the prepared component A inorganic binder are shown in the attached table.

The component B comprises the following raw materials in percentage by weight: 85% of anhydrite and 15% of lime. The technological process is the same as that of example 1, and the physical and chemical properties of the component B inorganic binder are shown in the attached table.

Example 3

The component A comprises the following raw materials in percentage by weight: 45% of limestone, 35% of aluminum oxide and 20% of gypsum. The firing temperature was 1400 ℃ and the other processes were the same as in example 1. The physical and chemical properties of the prepared component A inorganic binder are shown in the attached table.

The component B comprises the following raw materials in percentage by weight: 75% of gypsum and 25% of lime. Firstly, crushing gypsum to the granularity of 15-25 mm, calcining for 25 minutes at 950 ℃, and removing crystal water in the gypsum. Then the calcined gypsum and lime in the ingredients are ground in a mill to obtain grey white fine powder, namely the component B inorganic binder, and the physical and chemical properties of the component B inorganic binder are shown in the attached table. Attached watch

		Example 1		Example 2		Example 3
								Component A Binder	B component Binder	Component A Binder	B component Binder	Component A Binder	B component Binder
		Transforming Study the design Become into Is divided into (％)	CaO	40.6	46.2	47.4	43.5							42.2	48.7
SO3	8.5							40.3	6.5	42.5	8.2	37.5
			Al2O3	34.4	-	28.2	-						32.4	-
SiO2	9.2							-	8.4	-	8.7	-
			Fe2O3	4.8	-	4.3	-						3.6	-
Specific surface area m2/kg								385	315	381	305	383			310
		Specific gravity g/cm3		2.8	2.6	2.7	2.5						3.0	2.8

The granulation binder belongs to neutral alkali, and the pH value of the A, B two-component binder after water is added is about 8-9. And has no toxicity, no corrosion and no adverse effect on sintering and smelting.

The ratio of the binder of the component A to the binder of the component B in the binder for granulation is 1: 0.5-1. And adding the prepared granulating binder into the dedusting ash in a proportion of 3-7% of the weight of the dedusting ash, and fully mixing to obtain uniform mixed powder. And then adding water with the weight of 8-13% of the dedusting ash, namely granulating on a pelletizing disc to produce sintered dedusting ash green pellets, wherein the granularity of the green pellets is mostly 3-8 mm.

The field industrial test result shows that: the sintering dedusting green ball prepared by the granulating binder is added into the sintering mixture, so that the granulating effect of the sintering mixture can be obviously improved, and the sintering dedusting green ball plays a beneficial role in improving the air permeability of the sintering material and improving the mixing uniformity with fuel and the like in the sintering process. The yield of the sintering ore is improved by 2.355 percent, and the utilization coefficient of the sintering machine is improved by 0.03 t/m²H, the sintered fuel consumption is reduced by 1.3 Kg/t, the power consumption is reduced by 0.895 Kwh/t, and oilThe consumption is reduced by 0.205 Kg/t, the dust resource is fully utilized, the metal recovery rate of a sintering plant is improved by 0.02 percent, and the economic benefit is obvious.

The adhesive for granulating can also be used for the adhesive for granulating other metallurgical dust wastes.

Claims (3)

1. A binder for granulation, characterized in that: the binder for granulating consists of A, B two-component inorganic binder, wherein the A-component inorganic binder comprises the following chemical components in percentage by weight: 38-44% of CaO and SO₃6～10％、Al₂O₃28～38％、SiO₂Less than 10%, the balance being Fe₂O₃And other impurities; the component B comprises the following chemical components in percentage by weight: 40-52% of CaO and SO₃28-44% of the balance of other impurities; the ratio of the component A inorganic binder to the component B inorganic binder is 1: 0.5-1.

2. A method of manufacturing the binder for granulation according to claim 1, characterized in that:

the component A comprises the following raw materials in percentage by weight: 40-55% of limestone, 30-40% of alundum and 15-25% of gypsum, firing the ingredients at 1300-1400 ℃ to form clinker, grinding the clinker together to obtain the product with the specific surface area of more than 380m²Kg, specific gravity of 2.7-3.0 g/cm³The component A is an inorganic binder;

the component B comprises the following raw materials in percentage by weight: 70-90% of anhydrite and 10-30% of lime, and grinding the ingredients together to prepare the gypsum with the specific surface area larger than 300m²Kg, specific gravity of 2.5-2.8 g/cm³The component B of (1) an inorganic binder.

3. The method for producing a binder for granulation according to claim 2, characterized in that: the anhydrite in the component B raw material ingredients can also be gypsum calcined at the temperature of 800-1000 ℃ for 20-30minutes.