Method for inhibiting copper concentrate Isa smelting flue nodulation through calcium oxide injection

Abstract

The invention relates to a method for inhibiting copper concentrate Isa smelting flue nodulation through calcium oxide injection, and belongs to the technical field of thermometallurgy. According to the method, calcium oxide powder is blown into an uptake flue for Isa copper smelting and reacts with acidic flue gas to improve the acidic environment in the flue, a solid-phase substance cuprous oxide core on the flue is melted into a liquid phase under the fluxing action of the calcium oxide powder, and meanwhile, the solid-phase substance cuprous oxide core is separated from the liquid phase. The calcium oxide powder and the iron oxide are combined to generate a calcium ferrite substance with the melting point lower than the temperature of the flue, the liquid phase proportion in the nodulation substance in the flue is increased, the liquidity is enhanced, the nodulation substance naturally flows into a molten pool under the action of gravity, nodulation substance cores in the flue are reduced, and volatile impurity elements in smoke are prevented from being bonded; the generation of dense blocky nodulation substances in the flue is inhibited. According to the method, nodulation is inhibited through the synergistic effect of multiple reaction mechanisms of calcium oxide, and high adaptation and synergy with the Isa smelting process are achieved.

Description

Technical Field

[0001] The invention relates to a method for inhibiting the formation of nodules in a flue of copper concentrate Isa smelting by injecting calcium oxide, and belongs to the technical field of material preparation. Background Art

[0002] Nodule material has always been a key problem plaguing the copper pyrometallurgical smelting industry, especially the large amount of hard nodule material produced in the ascending flue during matte smelting. It not only causes the loss of metal elements, reduces heat exchange efficiency, and blocks the air flow channel, but also seriously damages refractory bricks and increases the risk of environmental pollution from harmful heavy metal dust. Regular shutdown of the furnace for blasting to remove nodule material is bound to affect stable production.

[0003] The strategies to inhibit flue nodules mainly include source control, process inhibition and terminal treatment. Most copper smelting enterprises still use manual knocking, mechanical vibration and blasting to break up nodules. This method is inefficient and ineffective, which will lead to the suspension of continuous production and affect benefits. Controlling the entry of volatile elements into the furnace from the source is the most effective and reliable method. It reduces the addition of elements such as As, Pb, and Zn at the source and avoids the occurrence of physical entrainment of smoke during the production process. However, with the increasing development of copper ore resources, the grade of copper ore continues to decline, the utilization rate of polymetallic associated ores has generally increased, and the difficulty of source control has increased. At present, the existing method to reduce the formation and agglomeration of nodules in the process is to use a spray gun to spray natural gas at the dense nodule area, and use the carbon monoxide produced by the combustion of natural gas to reduce the high-melting-point metal oxides such as Fe3O4 and CuFeO2 in the nodule material, and at the same time use the heat generated by the combustion to accelerate the melting of the nodule material and make it flow into the molten pool; or spray carbon powder or coal powder to reduce the As, Pb, and Zn oxides in the nodule material, so that it turns into a molten state and inhibits its nodulation behavior. This method has been adopted by some copper smelting enterprises, and to a certain extent, it has achieved the goal of inhibiting the growth rate of nodule materials, but the effect is less stable, and there are certain safety hazards in spraying natural gas or carbon powder.

[0004] In view of the technical problems existing in the above-mentioned current means of inhibiting nodulation substances, it is urgent to develop a safe and stable method for inhibiting nodulation substances. Summary of the invention

[0005] In view of the problem that it is difficult to suppress the nodulation in the existing copper Isa smelting flue, the present invention proposes a method for suppressing the nodulation in the copper concentrate Isa smelting flue by spraying calcium oxide, that is, by spraying calcium oxide powder into the Isa smelting ascending flue to neutralize the acidic environment in the flue, reduce the melting point of cuprous oxide in the inner core of the nodule material, and combine with iron oxide to form calcium ferrite, so that the inner core of part of the nodule material is transformed into a molten state. When the liquid phase proportion of the nodule material increases, the fluidity is enhanced, and it naturally flows into the smelting pool under the action of gravity, reducing the adhesion and aggregation of volatile elements on the inner core of the nodule material, thereby achieving the purpose of suppressing the growth of nodule material.

[0006] A method for inhibiting the formation of nodules in the flue of copper concentrate ISA smelting by injecting calcium oxide, characterized in that the specific steps are as follows: (1) Grinding and sieving calcium oxide to obtain calcium oxide powder; (2) Spraying calcium oxide powder into the ascending flue of the copper concentrate Isa smelting to react with the acidic flue gas to improve the acidic environment in the flue. The cuprous oxide core of the solid phase material on the flue is melted into a liquid phase under the fluxing effect of the calcium oxide powder. At the same time, the calcium oxide powder combines with the iron oxide to form a calcium ferrite material (in a molten state at the flue temperature) with a melting point not higher than the flue temperature (1220°C). The liquid phase proportion in the nodule material in the flue increases, the fluidity is enhanced, and it naturally flows into the molten pool under the action of gravity, reducing the core of the nodule material in the flue, avoiding the adhesion of volatile impurity elements (As, Pb, Zn) in the smoke, and inhibiting the formation of dense block nodule material in the flue.

[0007] Preferably, the particle size of the calcium oxide powder in step (1) is ≤50 μm.

[0008] Preferably, the amount of calcium oxide powder injected in step (2) accounts for 1-10% of the total mass of the smoke.

[0009] The beneficial effects of the present invention are: (1) The present invention aims at the problem of nodulation in the ascending flue of Isa smelting of copper concentrate, and proposes to use calcium oxide as an inhibitor, and utilize the neutralization effect of alkaline oxide (CaO) on the acidity of the flue, the fluxing effect on the solid phase material (Cu2O) in the inner core of the nodule material, and the combination with iron oxide to form low-melting-point calcium ferrite (CaFe2O5), so that the melting point of the inner core of the nodule material is lower than the flue temperature, the fluidity in the flue is increased, the adhesion to volatile impurity elements such as As, Pb, Zn in the smoke is reduced, the growth of nodule material is inhibited, and the generation of nodule material is greatly reduced; (2) The spraying of calcium oxide powder in the present invention will not have an adverse effect on the smelting of copper concentrate, will not produce flammable and explosive gases in the flue, and significantly improves the safety of inhibiting the production of nodule substances. DETAILED DESCRIPTION

[0010] The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.

[0011] Example 1: A method for inhibiting the formation of nodules in the flue of copper concentrate ISA smelting by injecting calcium oxide, the specific steps are as follows: (1) Grinding and sieving calcium oxide to obtain calcium oxide powder (particle size of 10-15 μm); (2) Spraying calcium oxide powder (2% of the mass of the flue gas) into the ascending flue of the Isa Copper Smelting Plant, reacting with the acidic flue gas to improve the acidic environment in the flue. The solid phase cuprous oxide (the core of the nodule material) on the flue is melted into a liquid phase in large quantities under the fluxing effect of the calcium oxide powder in the high temperature environment of the ascending flue. At the same time, the calcium oxide powder combines with the iron oxide to form a calcium ferrite material (in a molten state at the flue temperature) with a melting point not higher than the flue temperature (1220°C). The liquid phase proportion in the nodule material in the flue increases, the fluidity is enhanced, and it naturally flows into the molten pool under the action of gravity, reducing the core of the nodule material in the flue, avoiding the adhesion of volatile impurity elements (As, Pb, Zn) in the flue dust, and inhibiting the formation of dense block nodule material in the flue. In this embodiment, the addition of calcium oxide powder reduces the melting point of cuprous oxide and generates some calcium ferrite material, the porosity of the nodule material is significantly reduced, and the liquid phase ratio is increased to 25.63%.

[0012] Example 2: A method for inhibiting the formation of nodules in the flue of copper concentrate ISA smelting by injecting calcium oxide, the specific steps are as follows: (1) Grinding and sieving calcium oxide to obtain calcium oxide powder (particle size of 15-20 μm); (2) Spraying calcium oxide powder (5% of the total mass of flue dust) into the ascending flue of the copper concentrate Isa smelting to react with the acidic flue gas to improve the acidic environment in the flue. The solid phase cuprous oxide (the core of the nodule material) on the flue is melted into a liquid phase in large quantities under the fluxing effect of the calcium oxide powder in the high temperature environment of the ascending flue. At the same time, the calcium oxide powder combines with the iron oxide to form a calcium ferrite material (in a molten state at the flue temperature) with a melting point not higher than the flue temperature (1220°C). The liquid phase ratio in the nodule material in the flue increases, the fluidity is enhanced, and it naturally flows into the molten pool under the action of gravity, reducing the core of the nodule material in the flue, avoiding the adhesion of volatile impurity elements (As, Pb, Zn) in the flue dust, and inhibiting the formation of dense block nodule material in the flue. In this embodiment, the addition of calcium oxide powder reduces the melting point of cuprous oxide and generates some calcium ferrite material, the porosity of the nodule material is significantly reduced, and the liquid phase ratio is increased to 35.83%.

[0013] Example 3: A method for inhibiting the formation of nodules in the flue of copper concentrate ISA smelting by injecting calcium oxide, the specific steps are as follows: (1) Grinding and sieving calcium oxide to obtain calcium oxide powder (particle size of 5-10 μm); (2) Spraying calcium oxide powder (8% of the total mass of the flue gas) into the ascending flue of the Isa Copper Smelting Plant, reacting with the acidic flue gas to improve the acidic environment in the flue. The solid phase cuprous oxide (the core of the nodule material) on the flue is melted into a liquid phase in large quantities under the fluxing effect of the calcium oxide powder in the high temperature environment of the ascending flue. At the same time, the calcium oxide powder combines with the iron oxide to form a calcium ferrite material (in a molten state at the flue temperature) with a melting point not higher than the flue temperature (1220°C). The liquid phase proportion in the nodule material in the flue increases, the fluidity is enhanced, and it naturally flows into the molten pool under the action of gravity, reducing the core of the nodule material in the flue, avoiding the adhesion of volatile impurity elements (As, Pb, Zn) in the flue dust, and inhibiting the formation of dense blocky nodule material in the flue. In this embodiment, the addition of calcium oxide powder reduces the melting point of cuprous oxide and generates some calcium ferrite material, the porosity of the nodule material is significantly reduced, and the liquid phase ratio is increased to 42.15%.

[0014] Example 4: A method for inhibiting the formation of nodules in the flue of copper concentrate ISA smelting by injecting calcium oxide, the specific steps are as follows: (1) Grinding and sieving calcium oxide to obtain calcium oxide powder (particle size of 1-5 μm); (2) Spraying calcium oxide powder (10% of the total mass of the flue gas) into the ascending flue of the Isa Copper Smelting Plant to react with the acidic flue gas to improve the acidic environment in the flue. The solid phase cuprous oxide (the core of the nodule material) on the flue is melted into a liquid phase in large quantities under the fluxing effect of the calcium oxide powder in the high temperature environment of the ascending flue. At the same time, the calcium oxide powder combines with the iron oxide to form a calcium ferrite material (in a molten state at the flue temperature) with a melting point not higher than the flue temperature (1220°C). The liquid phase proportion in the nodule material in the flue increases, the fluidity is enhanced, and it naturally flows into the molten pool under the action of gravity, reducing the core of the nodule material in the flue, avoiding the adhesion of volatile impurity elements (As, Pb, Zn) in the flue dust, and inhibiting the formation of dense blocky nodule material in the flue. In this embodiment, the addition of calcium oxide powder reduces the melting point of cuprous oxide and generates some calcium ferrite material, the porosity of the nodule material is significantly reduced, and the liquid phase ratio is increased to 48.26%.

[0015] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for inhibiting the formation of nodules in the flue of copper concentrate ISA smelting by injecting calcium oxide, characterized in that: The specific steps are as follows: (1) Grinding and sieving calcium oxide to obtain calcium oxide powder; (2) Spraying calcium oxide powder into the ascending flue of the copper concentrate Isa smelting to react with the acidic flue gas to improve the acidic environment in the flue. The cuprous oxide core of the solid phase material on the flue is melted into a liquid phase under the fluxing effect of the calcium oxide powder. At the same time, the calcium oxide powder combines with the iron oxide to form a calcium ferrite material with a melting point lower than the flue temperature. The liquid phase proportion in the nodule material in the flue increases, the fluidity is enhanced, and it naturally flows into the molten pool under the action of gravity, reducing the core of the nodule material in the flue, avoiding the adhesion of volatile impurity elements in the smoke, and inhibiting the formation of dense block nodule material in the flue.

2. The method for inhibiting the formation of nodules in the flue of copper concentrate ISA smelting by calcium oxide injection according to claim 1, characterized in that: The particle size of the calcium oxide powder in step (1) is ≤50 μm.

3. The method for inhibiting the formation of nodules in the flue of copper concentrate ISA smelting by calcium oxide injection according to claim 1, characterized in that: The amount of calcium oxide powder injected in step (2) accounts for 1-10% of the total mass of the smoke.