CN1390962A

CN1390962A - Process for refining raw copper bynon-oxidizing nitrogen-doping reducing pyrometallurgy

Info

Publication number: CN1390962A
Application number: CN 02120509
Authority: CN
Inventors: 周松林; 黄永峰
Original assignee: JINLONG COPPER CO Ltd
Current assignee: JINLONG COPPER CO Ltd
Priority date: 2002-05-22
Filing date: 2002-05-22
Publication date: 2003-01-15
Anticipated expiration: 2022-05-22
Also published as: CN1184337C

Abstract

A technology for refining crude copper features that at the blowing stage in converter, the contents of S and O in discharged copper are reasonably controlled, the nitrogen instead of air is used for discharge slags, and at reducing stage the nitrogen gas is proportionally added to reducer. Its advantages are simple operation, short period, high productivity, less energy consumption and no smoke pollution.

Description

Crude copper non-oxidation nitrogen-doping reduction fire refining process

(I) technical field

The invention relates to a crude copper fire refining process, in particular to a crude copper oxidation-free nitrogen-doped reduction fire refining process.

(II) background of the invention

The pyrometallurgical process of world mineral copper generally comprises the steps of copper sulfide concentrate smelting to matte, converting to blister copper, pyrometallurgical refining to anode copper and electrolyzing to high-purity cathode copper. Before entering the electrolytic process, the blister copper must be refined by an anode furnace fire method so as to produce an anode plate with chemical components and physical specifications meeting the electrolytic requirements. The traditional fire refining process is an oxidation-reduction process, which is mainly characterized in that liquid crude copper blown by a converter is poured into an anode furnace, air (or oxygen-enriched air) is blown into the anode furnace for oxidation, impurities are generated into oxides for slagging or volatilization removal, then a reducing agent is blown into the anode furnace for reduction removal of redundant oxygen, and then a qualified anode plate can be cast. The method is generally adopted in crude copper fire refining processes of copper smelting plants at home and abroad at present, and has the main defects that oxidation and reduction are two opposite operation processes, the operation period is long, the production efficiency is low, the energy consumption is high, and black smoke pollution is serious.

Disclosure of the invention

The invention aims to overcome the defects of the traditional crude copper fire refining process, and cancels the traditional oxidation operation process, while the reduction operation adopts nitrogen-doped reduction. The fire refining process has the advantages of simple operation, short operation period, high production efficiency and low energy consumption, eliminates black smoke pollution and is easy to realize large-scale industrial production.

The non-oxidation process provided by the invention is to reasonably control the copper discharging end points [ S]and [ O]of the converter, namely properly blowing for 1-5 minutes when the end points are approached to ensure that the [ S]content is 0.025-0.040%, (250-. Although the S content in the copper liquid does not reach the S content below 50ppm of the traditional oxidation end point, the invention is characterized in that part of sulfur can still be removed in the reduction process, and part of oxidation desulfurization task is replaced by the reduction process, i.e. the sulfur does not need to be completely removed before the reduction.

The principle of the non-oxidation process is as follows:

in conventional redox pyrometallurgical refining, the main purpose of oxidation is to remove impurities and sulphur from the blister copper and the purpose of reduction is to remove excess oxygen brought into the blister copper by oxidation. For the mineral blister copper, the main role of the pyrometallurgical oxidation of mineral copper is sulphur removal, since most of the impurities have been removed in the first two steps (smelting and converting). In order to eliminate the oxidation process of the anode furnace, the key point is to provide a new method for effectively removing the sulfur in the copper water without additionally increasing the oxygen content in the anode furnace.

Firstly, the oxidation mechanism of the anode furnace is analyzed, when air is blown into the anode furnace and the copper liquid is oxidized, the copper liquid occupies the main body, so the copper liquid is used for oxidationOxygen in the air reacts with sulfur in the copper liquid for the most part, and reacts with copper to generate cuprous oxide When being Cu₂After the solubility of O in the copper bath reaches saturation, i.e. at the operating temperature, Cu₂When the solubility of O in the copper liquid reaches 8% -12%, the desulfurization reaction It is performed vigorously. The production practice shows that: before 2.0 hours of oxidation, the desulfurization effect is not great, and when Cu appears on the surface of the copper liquid₂When O is separated out to be glossy, the desulfurization reaction is quickly carried out, and the sulfur is basically completely removed after ten minutes, so that the final sample application of the traditional standard oxidation is achieved, namely[S]＝20-50ppm，[O]5500 and 8000 ppm. At present, the traditional deep oxidation operation process is basically adopted by copper smelting plants at home and abroad. The oxidation operation not only increases the operation time and reduces the production efficiency, but also excessively increases the oxygen content in the copper liquid and increases the reduction burden, thereby prolonging the reduction time and increasing the consumption of the reducing agent.

As can be seen from the oxidation mechanism, the oxidation time of the anode furnace is mostly consumed in the generation of Cu₂On the basis of the situation, the sulfur in the blister copper can be effectively removed by over-blowing the converter for a certain time so as to achieve the purpose of eliminating the oxidation of the anode furnace. However, the converter has a large amount of blast air, and the reaction in the converter is severe. If the converter is over-blown to contain [ S]]S content when the amount reaches the oxidation end point of the anode furnace]When the amount is less than 50ppm, the oxygen content in the molten copper becomes too high, so that the converter tends to generate slag and Cu tends to be formed₂The volatilization of O is lost, resulting in production difficulties. The copper discharging end point of the traditional converter is generally S]＝400-550ppm、[O]3000 and 4000 ppm. Through continuous research and experiment, a suitable converter copper discharging terminal point which can ensure normal production and can eliminate the oxidation process of the anode furnace is found to be S]＝250-400ppm、[O]4000 and 5000 ppm. I.e. over-blowing for 1-5 minutes at the traditional copper tapping end point of the converter.

The nitrogen doping reduction process is to mix a certain proportion of inert gas nitrogen into reducing agent for reduction.

The principle of the nitrogen doping reduction process is as follows:

the copper liquid contains a large amount of oxygen which is not beneficial to casting and electrolysis, and excessive oxygen is required to be reduced and removed by a reducing agent. The reducing agent generally comprises firewood, pulverized coal, diesel oil, heavy oil, Liquefied Petroleum Gas (LPG), natural gas, hydrogen, ammonia gas and the like. The most commonly used reductants are typically hydrocarbons such as heavy oil, diesel, LPG, natural gas, and the like. Due to the pure reducing agent inThe stirring strength in the copper liquid is not large, the contact time with the copper liquid is short and insufficient, most of carbon and hydrogen pyrolyzed at high temperature by a reducing agent are not ready to be mixed with [ O]in the copper liquid]The contact reaction escapes from the surface of the copper liquid and is discharged, and particularly, the cracked carbon has poor activity and weak reducing capability and most of the cracked carbon becomes carbon black and is discharged. Therefore, the phenomenon of low reduction efficiency generally exists in the reduction operation of pure reducing agent for the anode furnace, and the reduction efficiency is generally about 20-35%. Therefore, not only is a great amount of reducing agent wasted, but also black smoke pollution is caused, and the atmospheric pollution is caused, which is a common problem in the anode furnace fire refining in the world. The invention adopts the nitrogen doping process for reduction, and after the reducing agent is mixed with inert gas nitrogen and blown into the copper liquid, the stirring strength of the copper liquid is enhanced, the dynamic condition of the reduction reaction is improved, and partial SO dissolved in the copper liquid can be driven out₂And the gas is mixed, so that the reducing efficiency of the reducing agent is improved, the consumption of the reducing agent is reduced, and the problem of black smoke pollution is solved. In addition, the existence of the nitrogen also prevents the surface of the copper liquid from contacting with air, and prevents the phenomenon of re-dissolved oxygen.

The invention has other characteristics that:

one of the characteristics is as follows: namely reduction with sulfur. From the conventional oxidation viewpoint, after sulfur must be completely oxidized and removed, reduction operation, namely deep oxidation operation, is carried out, and through a plurality of experimental researches and grops, partial sulfur can be found before reduction, and the partial sulfur can be removed in a reduction stage, and the principle is as follows: [ S]in molten copper]Mainly by Cu dissolved in copper liquid₂S and SO₂Are present. While the reduction reaction is carried out, byMixed gas (reducing agent + N)₂) Stirring to make Cu in the copper liquid₂S and Cu₂Formation of SO by collision and combination of O₂The precipitate is carried out with nitrogen bubbles. In addition, the presence of nitrogen reduces SO₂Partial pressure of (3) and temperature of the copper bath, thereby reducing SO₂Solubility in copper bath, SO precipitated₂Is carried out along with the nitrogen bubbles, thereby achieving the purpose of removing sulfur.

The second characteristic: when the rotary anode furnace is used for deslagging, air is generally blown into the furnace, so that the deslagging can be realized through stirring, the copper can be prevented from being poured into a tuyere, the oxygen content in the copper liquid can be increased, and the reduction load is increased. The present invention uses nitrogen instead of air to solve this problem.

Thirdly, the characteristics are as follows: the invention uses nitrogen when shaking the furnace. When the furnace is shaken conventionally, a reducing agent is generally used, and because the reducing agent is close to the copper liquid during shaking, the utilization rate of the reducing agent is very low, the anode furnace can emit serious black smoke during the rotation of the furnace. The invention solves the problem by stopping the feeding of the reducing agent and only introducing nitrogen when the furnace rotates.

The technological parameters of the invention when the anode furnace is used for refining the crude copper are as follows:

and (3) converter copper discharging end point control: insect copper-plate copper

Cu：99.00-99.50％ S：0.025-0.O40％ O₂：0.40-0.50％

Nitrogen gas: containing N₂: over 99 percent

Flow rate: 50-600Nm³/h

Temperature: 60-80 deg.C

The furnace charging pressure: 0.35-0.45MPa

Flow rate of reducing agent: 50-400Nm³/h

Pressure: 0.30-0.35Mpa

The operation time is as follows: 2.0-2.5 hours/furnace (450 tons/furnace)

The invention has the following advantages:

1. the produced anode plate contains 99.5-99.8% of Cu, 0.002-0.005% of S and 0.13-0.2% of O. The chemical components completely meet the electrolysis requirement.

2. The produced anode plate has no flash and burr, the surface is smooth, the structure is compact, and the qualified product rate is improved from 93 percent to 98 percent.

3. The operation time is shortened by half, namely for 450 tons of anode furnaces, the operation time is reduced from 4.5-5.0 hours per furnace of the traditional oxidation-reduction process to 2.0-2.5 hours per furnace, and the production capacity is improved by 50% under the same equipment condition. In addition, the unit consumption of heavy oil is reduced by 30 percent.

4. The unit consumption of the reducing agent is reduced by 50 percent, for example, the unit consumption of LPG is reduced to below 3.0kg/t-Cu from the original 6.0 kg/t-Cu.

5. The blackness of the discharged black tobacco is reduced from 4.0 to 1.0, and the pollution of the black tobacco is basically eliminated.

(IV) description of the drawings

FIG. 1 is a flow diagram of a conventional fire refining process, which is shown as having an oxidation operation.

FIG. 2 is a flow chart showing the process of the present invention in which the oxidation process is removed and nitrogen is added during the slagging and reduction process.

FIG. 3 is a flow chart of the equipment for the nitrogen-doping process without oxidation using a rotary anode furnace, using a gaseous reducing agent, as detailed in example 1.

FIG. 4 is a schematic view of a structure of a porous plug air brick additionally arranged at the bottom of a rotary anode furnace. The right side is a left view. See example 2 for a detailed description.

FIG. 5 is a flow diagram of an apparatus for a nitrogen-doping process without oxidation using a reflective anode furnace, using a liquid reductant, as described in example 3.

(V) detailed description of the preferred embodiments

Example 1:

as shown in figure 3, liquid crude copper is loaded into a rotary anode furnace (10), nitrogen is blown in for deslagging, and waste nitrogen discharged from an oxygen production station is passed through the nitrogenThe compressor (2) is conveyed into a nitrogen tank (3) for storage, and when the smelting operation is needed, N is firstly opened₂Adjusting valve (8), reducing nitrogen to 0.35-0.40 Mpa through pressure reducing valve (4), heating by heater (5), observing pressure gauge (6) and flowmeter (7), rotating anode furnace (10), embedding spray gun (11) 600-800 mm below copper liquid level, then opening adjusting valve (1) (50% of valve degree), and mixing reducing agent and N₂Fully mixed in a mixing container (9), and then the required reducing agent and N are adjusted by adjusting a valve (1) and a valve (8) reasonably₂Flow of (2) N₂Reducing agent is 1.0-1.5, and reduction operation is carried out until the end point.

Example 2:

as shown in FIG. 4, in order to enhance the stirring performance of molten copper and improve the reaction kinetics during the refining of blister copper in a rotary anode furnace, a plurality of porous plug air bricks (16) (2 in this embodiment) can be additionally arranged at the bottom of the furnace (10) according to the size and the copper loading of the furnace, so that N is used for refining blister copper₂+ spraying reductant into the melt from the furnace bottom. And reasonably controlling N according to the height of the copper liquid level₂And (4) pressure.

Example 3:

when the reflection type anode furnace (15) is used, the flow rate of the reducing agent is adjusted by the adjusting valve (1), and the flow rate of the gear flowmeter (13) is observed, so that the reducing agent enters the inner cavity of the nozzle (14) as shown in fig. 5. The nitrogen is conveyed to a gas storage tank (3) for storage through a nitrogen compressor (2), and when the nitrogen is used, the nitrogen is adjusted to a reasonable nitrogen flow value (generally controlled to be N) through a pressure reducing valve (4) and a flow meter (7) and an adjusting valve (8)₂1.0-1.3) nitrogen is fed into the outer cavity of the nozzle (14) to fully mix the reducing agent in the mixing cavity at the front end of the nozzle. Due to the high-pressure impact action of the nitrogen, the reducing agent is quickly changed into a dispersed state and is sprayed into the copper liquid in the reverberatory furnace (15) to enter the reduction operation, thereby improving the reduction efficiency.

Claims

1. A crude copper non-oxidation nitrogen-doping reduction fire refining process is characterized in that liquid crude copper blown by a converter is poured into an anode furnace for refining to form an anode plate, the process is characterized in that the converter is properly blown for 1-5 minutes when the blowing of the converter is close to the end point, the [ S]and [ O]of the copper outlet end point after the blowing of the converter are reasonably controlled, namely the [ S]content is 0.025-0.040%, the [ O]content is 0.40-0.50%, and the oxidation operation process of the anode furnace is cancelled; during the reduction operation, a certain proportion of inert gas nitrogen is mixed into the reducing agent for reduction.

2. The non-oxidizing nitrogen-doped reducing fire refining process as recited in claim 1, wherein during slag discharge in the rotary anode furnace, nitrogen gas is blown into the molten copper in the furnace to replace the original blown air for slag discharge.

3. The non-oxidizing nitrogen-doped reducing fire refining process as claimed in claim 1 or 2, wherein the feeding of the reducing agent is stopped during the rotation of the furnace while shaking the furnace, and only nitrogen gas is fed.

4. The non-oxidizing nitrogen-doped reducing fire refining process as recited in claim 1 or 3, wherein when a rotary anode furnace is used, a plurality of porous plug air bricks are additionally arranged at the bottom of the anode furnace.

5. The non-oxidizing nitrogen-doped reducing fire refining process as recited in claim 1, wherein when a rotary anode furnace is used, N is fed thereto₂(99% or more) flow rate of 50 to 600Nm³The temperature is 60-80 ℃; the flow of the input reducing agent is 50-400Nm³/h，N₂1.0-1.5% reducing agent.

6. The non-oxidizing nitrogen-doped reducing fire refining process as recited in claim 1, wherein when a reverberatory anode furnace is used, the flow rate of the reducing agent and nitrogen is adjusted, and after the reducing agent and nitrogen are fully mixed in the mixing chamber at the front end of the nozzle, the reducing agent is rapidly changed into a dispersed state and is sprayed into the copper liquid in the reverberatory furnace through the nozzle to perform the reduction operation.