CN103451451A - Ferro-nickel alloy production technology with laterite nickel ore processed through oxygen enrichment hot air shaft furnace - Google Patents

Abstract

The invention discloses a process for producing ferronickel alloy by processing laterite nickel ore in an oxygen-enriched hot blast shaft furnace, belonging to the field of laterite nickel ore production. It is characterized in that lateritic nickel ore is used as the main raw material, mixed with a certain amount of reducing agent, flux and water, fully mixed, pressed into balls by a ball press machine, dried and sent to an oxygen-enriched hot blast shaft furnace for smelting, and finally obtained Nickel-containing molten iron, high calorific value gas and slag are melted and cast into ingots to obtain nickel-iron alloy, and high calorific value gas and slag are recycled and utilized. The invention has the advantages of simple production process, easy operation, strong raw material adaptability, high processing efficiency, etc., can efficiently process different types of laterite nickel ore, produce nickel-iron alloy, and can perform physical heat and chemical With the utilization of heat, the generated slag can also be utilized as a resource, which has very significant economic and environmental benefits.

Description

A process for producing nickel-iron alloy by treating laterite nickel ore with oxygen-enriched hot blast shaft furnace

technical field

The invention belongs to the field of laterite nickel ore production, and relates to a nickel-iron alloy production process, in particular to a process for producing nickel-iron alloy by using a shaft furnace to process laterite nickel ore.

Background technique

Nickel has the advantages of oxidation resistance, corrosion resistance, high temperature resistance, good ductility, and high strength. It is widely used in the production of key materials such as stainless steel and high-temperature alloy steel, and is an important strategic metal. The mineral resources of nickel are mainly divided into nickel sulfide ore and laterite nickel ore. Among them, nickel sulfide ore accounts for 30% to 40% of the nickel resources available for mining in the world, and nickel oxide ore accounts for 60% to 70%. Limited, and after long-term mining, its reserves have declined sharply, and it is facing an increasingly depleted situation. However, laterite nickel ore is rich in resources, low in mining costs, and has obvious resource advantages. It will be the main source of nickel in the future.

In recent years, with the increasing demand for nickel-iron alloys in the stainless steel industry, the lateritic nickel ore smelting nickel-iron alloy industry has developed rapidly in China. The traditional sintering-blast furnace process for treating laterite nickel ore (Nonferrous Metallurgy Design and Research, 2012, 33(5): 16) has the disadvantages of high energy consumption and serious pollution, and has been gradually eliminated. In recent years, the rotary kiln-electric furnace process The representative coal-based direct reduction process (such as Chinese patent 200910067714.3) has been widely used at home and abroad, but this process also has disadvantages such as process plant, high energy consumption, easy ring formation in the rotary kiln, and low processing efficiency. Hanking Industrial Group Co., Ltd. invented a method of smelting laterite nickel ore by using wet ball into the furnace for low-temperature reduction. This method uses wet ball into the furnace to replace the traditional sintering process, which not only reduces pollution and energy consumption, but also The wet bulb can also play a role in filtering smoke and dust during smelting. In addition, the process adopts a low-temperature smelting method, which can increase the nickel content in ferronickel, and is a better treatment process for laterite nickel ore. On the whole, there is still a lot of room for development in the treatment of laterite nickel ore in my country, and there is an urgent need to develop an efficient treatment process for laterite nickel ore suitable for my country's national conditions.

Contents of the invention

The invention relates to a new process for efficiently treating laterite nickel ore to produce nickel-iron alloy by using an oxygen-enriched hot blast shaft furnace. The process can process laterite nickel ore of different grades to produce nickel-iron alloy with different nickel content, and can also obtain high calorific value gas and Slag and other by-products.

The present invention uses laterite nickel ore as the main raw material, mixes a certain amount of reducing agent, flux and water, and after fully mixing, presses it into balls by a briquetting machine. The molten nickel-iron, high calorific value gas and slag are melted and cast into ingots to obtain nickel-iron alloy, and the high calorific value gas and slag can be recycled and utilized. Technical scheme of the present invention is:

(1) Dry the laterite nickel ore, remove the free water in the mineral, grind it to a specified particle size (less than 10 mesh), and send it to the laterite nickel ore batching bin;

(2) Add 5-10% reducing agent (anthracite, coke powder), 0-20% flux (quicklime, limestone) and 5-15% water to the laterite nickel ore, mix well and pass through the roller ball press Or press it into blocks with a vibrating ball press, and dry it for later use. This process can replace the sintering process to reduce pollution and energy consumption;

(3) Smelting raw materials such as laterite nickel ore pellets, coke, flux, etc. are sent to the top silo of the shaft furnace by the belt conveyor, and added to the shaft furnace according to the production ratio for high-temperature smelting.

Above 900°C is the upper area of the shaft furnace, where the charge is gradually heated to complete the decomposition of carbonates and other substances and the evaporation of crystal water, and at the same time part of the metal oxides are reduced, mainly by indirect reduction, but due to the reaction The temperature is low and the reaction time is short, and the degree of reduction is weak;

900～1300℃ is the middle part of the shaft furnace. At this stage, the rapid reduction of oxides such as iron and nickel can be realized, and the charge begins to melt. By controlling the amount of carbon in the pellets, the selective reduction of the pellets can be realized. The nickel oxide has poor stability and can basically be completely reduced, existing in the form of metallic nickel, while the iron oxide is partially reduced, as metallic iron and Exist in the form of ferrous oxide.

Above 1300°C is the lower part of the melting furnace. At this stage, the reduced charge passes through hot coke to form slag and molten iron, nickel enters the molten iron, and unreduced FeO enters the slag phase.

(4) The lower part of the shaft furnace burns coke, releases heat, and produces high-temperature reducing furnace gas. The furnace charge contacts with hot coke and high-temperature furnace gas to perform intense heat exchange, and completes the preheating, reduction, and melting of laterite nickel ore pellets. , slag iron separation and other metallurgical processes, and finally produce nickel-containing molten iron, slag and high calorific value gas.

Since the economic value of nickel is much higher than that of iron, during the smelting process of lateritic nickel ore, we hope that nickel will be reduced as much as possible, while iron will be reduced as little as possible, so as to improve the grade of nickel in ferronickel. Hanwang Industrial Group Co., Ltd. adopts the method of low-temperature smelting. The smelting temperature is about 1260 ℃ ~ 1380 ℃, so that nickel is preferentially reduced in the reduction zone, and iron is partially reduced, thereby increasing the nickel content in ferronickel. The present invention adopts a low-carbon, high-temperature, high-efficiency smelting method. The carbon content of laterite nickel ore pellets only needs to meet the reduction of nickel and part of iron. A tuyere is provided at the lower part of the shaft furnace, and a hot blast stove is equipped. During smelting, oxygen-enriched hot air (hot air temperature 700-1000°C, oxygen-enriched rate 1-10%) is blown into the furnace through the tuyere, making the maximum temperature in the furnace reach 2000°C, which greatly speeds up the laterite nickel ore pellets in the furnace. In the smelting process, the reduction time is shortened, most of the nickel is reduced, and part of the iron is reduced, and finally the selective reduction of the laterite nickel ore pellets is realized, and the nickel grade in the ferronickel is improved.

The nickel-containing molten iron and slag are discharged out of the furnace by siphoning. This process is similar to the principle of a U-shaped tube. The molten iron and slag can be discharged out of the furnace through this device. The advantage of this process is to reduce the slag stay in the shaft furnace time, reduce the reduction of FeO in slag, and increase the nickel grade of molten iron. The nickel-containing molten iron is melted and cast into ingots, with a nickel content of 6-15%; the slag is treated by a granulation device, and the slag flowing out of the slag outlet is quenched and crushed with water. The alkalinity of the slag is about 0.9-1.0, which can be used as building materials or Further comprehensive utilization.

After the gas is purified and dedusted, its sensible heat can be used to preheat the combustion-supporting air of the hot blast stove and dry the moist laterite nickel ore. At the same time, the gas can be used as the gas fuel of the hot blast stove burner, making full use of the physical heat and chemical heat of the gas.

In order to solve the smoke and dust pollution problem in the smelting process of laterite nickel ore, Hanking Industrial Group Co., Ltd. invented the smelting operation of wet ball into the furnace. The wet ball can filter the smoke and dust in the material distribution area of the smelting furnace, thereby reducing the smoke and dust content in the flue gas. An annular furnace gas collection chamber is provided below the upper silo of the shaft furnace involved in the present invention. The flue gas is discharged from the annular gas collection chamber, and the pressure at the charging port on the top of the furnace is close to zero. At the same time, the exhausted flue gas enters the dry dedusting and wet dedusting systems to obtain dry dedusting ash, wet sludge and gas, which can be recycled again .

The notable feature of the present invention is that the utilization coefficient of laterite nickel ore treated by oxygen-enriched hot blast shaft furnace is very high, which can reach 9t/(m ³ ·t), which is more than 3 times of blast furnace utilization coefficient. By controlling the laterite nickel ore pellet The amount of carbon can be used to achieve selective reduction. Basically all nickel is reduced and enters the molten iron. Part of the iron oxide is reduced to molten iron, and the other part enters the slag in the form of FeO, thereby improving the nickel grade of the molten iron.

The invention has the advantages of simple production process, easy operation, strong raw material adaptability, high processing efficiency, etc., can efficiently process different types of laterite nickel ore, produce nickel-iron alloy, and can perform physical heat and chemical With the utilization of heat, the generated slag can also be utilized as a resource, which has very significant economic and environmental benefits.

Description of drawings

Figure 1 is a flow chart of the process for producing nickel-iron alloys from laterite nickel ore using an oxygen-enriched hot blast shaft furnace.

Detailed ways

The technological process of the present invention is: laterite nickel ore drying → batching → ball pressing → shaft furnace charging → preheating → reduction → melting → separation of slag and iron. The specific technological process is shown in Figure 1. The present invention will be further described below in conjunction with embodiment.

Implementation mode one:

The composition of laterite nickel ore selected is Ni: 1.30%, Fe: 25%; anthracite powder is used as reducing agent, its fixed carbon content is about 80%, ash content is about 12%, and volatile matter is about 8%; limestone powder is used as Flux, its CaO content is about 52%. Add the laterite nickel ore to the dryer for drying, and crush it to below 10 mesh by the crusher. Add anthracite powder, limestone powder and water according to the ratio of laterite nickel ore: anthracite powder: flux: water about 100:6:20:17 , mixed thoroughly, pressed into blocks under a pressure of not less than 20MPa, dried and put into the stock yard.

Put the dried laterite nickel ore pellets and coke into the shaft furnace, and blow oxygen-enriched hot air into the tuyere at the lower part of the shaft furnace. , release a lot of heat, this area is the highest temperature of the shaft furnace, the temperature can reach 2000 ℃. The high-temperature furnace gas generated by the tuyeres goes upwards to contact with the charge for intense heat exchange, providing the heat required for the preheating, reduction, melting and separation of slag and iron of the laterite nickel ore, and finally produces nickel-containing molten iron and slag, and the nickel-containing molten iron is siphoned The system is discharged out of the furnace and melted into ingots. The part of the shaft furnace above 900 °C mainly completes the preheating of laterite nickel ore pellets, the part of 900-1300 °C mainly completes the direct reduction of iron oxides and nickel oxides in the laterite nickel ore pellets, and the part of the shaft furnace below 1300 °C mainly completes the laterite nickel ore The melting of pellets and the separation of slag and gold take about 1.5 to 2 hours for the whole smelting process.

In the nickel-iron alloy obtained in this example, the nickel content is about 5.5-7%, the iron content is about 89-90.5%, the iron yield is about 60-80%, and the nickel yield is greater than 90%. The gas composition is about CO:CO ₂ :N ₂ =40:5:54, and the gas contains a lot of physical heat and chemical heat.

Implementation mode two:

The composition of laterite nickel ore selected is Ni: 1.80%, Fe: 20%; coke powder is used as reducing agent, its fixed carbon content is about 85%, ash content is about 13%, and volatile matter is about 2%; limestone powder is used as Flux, its CaO content is about 52%. Add the laterite nickel ore to the dryer for drying, and crush it to below 10 mesh by the crusher. Add coke powder, limestone and water according to the ratio of laterite nickel ore: coke powder: flux: water about 100:5:20:17, After fully mixing, press into blocks under a pressure of not less than 20MPa, and put them into the stockyard after drying. Put the dried laterite nickel ore pellets and coke into the oxygen-enriched hot blast shaft furnace for smelting, and the smelting process is similar to Embodiment 1.

In the nickel-iron alloy obtained in this example, the nickel content is 7-12%, the iron content is 84-89%, the iron yield is 60-80%, and the nickel yield is greater than 90%. The gas composition is about CO:CO ₂ :N ₂ =38:7:54.

Claims (4)

1. one kind is utilized the oxygen-enriched hot air shaft furnace to process the laterite nickel ore and producing ferronickel alloy prior, it is characterized in that take that red soil nickel ore is as main raw material, with addition of a certain amount of reductive agent, flux and water, fully mix by ball press compacting balling-up, send into the oxygen-enriched hot air shaft furnace after oven dry and smelted, finally obtain nickel-containing molten iron, high heating value gas and slag, the nickel-containing molten iron founding becomes ingot, obtain Rhometal, high heating value gas and slag are circulated and are utilized, and concrete technical scheme is:

(1) red soil nickel ore is carried out to drying, remove the free water in mineral, levigate 10 orders that are less than, send into the red soil nickel ore batch bin;

(2) allocate 5～10% reductive agent, 0～20% flux and 5～15% water in red soil nickel ore into, fully mix by pair roller ball press or vibration ball-pressing machine briquetting, standby after drying; Reductive agent is hard coal, coke powder, and flux is unslaked lime, Wingdale;

(3) red soil nickel ore pelletizing, coke, flux raw materials for metallurgy are sent to the shaft furnace furnace top bin by rotary conveyor, by producting proportion, add shaft furnace, carry out pyrotic smelting;

More than 900 ℃, be the shaft furnace upper area, furnace charge is heated gradually in this zone, completes decomposition and the crystallization evaporation of water of the materials such as carbonate, the part metals oxide compound is reduced simultaneously, and mainly take indirect reduction as main, but because temperature of reaction is low and the reaction times is short, reducing degree a little less than;

900～1300 ℃ of middle parts that are shaft furnace, this stage can be realized the fast restore of the oxide compounds such as iron, nickel, furnace charge starts melting; By controlling the mixed carbon comtent in pelletizing, can realize the selective reduction of pelletizing, the poor stability of nickel oxide, the nickel reduction ratio is greater than 90%, with the form of metallic nickel, exist, and ferriferous oxide partly is reduced, and with the form of metallic iron and iron protoxide, exists;

More than 1300 ℃, be the bottom of melting furnace, in this stage, the furnace charge reduced, through red-hot coke, forms slag and molten iron, and nickel enters in molten iron, and the FeO be not reduced enters the slag phase;

(4) shaft furnace bottom coke burning, emit heat, produce the reductibility furnace gas of high temperature, furnace charge contacts with red-hot coke and high-temperature furnace gas, carry out fierce heat exchange, the preheating, reduction, fusing, the slag iron that complete the red soil nickel ore pelletizing separate metallurgical process, finally generate nickel-containing molten iron, slag and high heating value gas.

2. a kind of oxygen-enriched hot air shaft furnace that utilizes is processed the laterite nickel ore and producing ferronickel alloy prior according to claim 1, it is characterized in that being provided with air port in the shaft furnace bottom, and outfit hotblast stove, during smelting, oxygen-enriched hot air is blown in stove by air port, make top temperature in stove reach 2000 ℃, 700～1000 ℃ of oxygen-enriched hot air temperature, oxygen enrichment percentage 1～10%.

3. a kind of oxygen-enriched hot air shaft furnace that utilizes is processed the laterite nickel ore and producing ferronickel alloy prior according to claim 1, it is characterized in that nickel-containing molten iron and slag adopt the mode of siphon to discharge out of the furnace, and nickel-containing molten iron becomes ingot through founding, and nickel content is 6～15%; Slag adopts granulating device to process, slag water quenching, fragmentation that slag notch is flowed out, and the basicity of slag is 0.9～1.0, as material of construction or further comprehensive utilization.

4. a kind of oxygen-enriched hot air shaft furnace that utilizes is processed the laterite nickel ore and producing ferronickel alloy prior according to claim 1, the below that it is characterized in that shaft furnace top feed bin is provided with annular furnace gas collection chamber, flue gas is discharged from annular gas-collecting chamber, the pressure of top charging mouth is close to zero, in the Metal In Shaft Furnace process, furnace roof does not have flue gas to diffuse, simultaneously, the flue gas of discharging enters dry method dust and wet method dedusting system, obtain dry gas cleaning ash, wet type mud and coal gas, dry gas cleaning ash, wet type mud and coal gas all carry out recycle again, take full advantage of physical thermal and the chemical heat of coal gas.

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