WO2024239502A1 - Apparatus and method for smelting nickel alloy with suspension roaster-electric furnace - Google Patents

Abstract

The present invention provides an apparatus and method for smelting a nickel alloy with a suspension roaster-electric furnace. The apparatus comprises a feeding system, a magnetizing roasting system, a discharging system, and an electric furnace system connected in sequence. The magnetizing roasting system comprises a cyclone preheater, a main suspension roaster, a cyclone separator, and a reaction chamber. A discharging port of the feeding system is connected to a feeding port of the cyclone preheater; a discharging port of the cyclone preheater is connected to an air inlet in a lower end of the main suspension roaster; a gas outlet of the cyclone preheater is connected to a feeding port of a cyclone dust remover; a discharging port of the cyclone dust remover is connected to a feeding port in an upper end of the main suspension roaster; a discharging port of the main suspension roaster is connected to a feeding port of the reaction chamber; a discharging port of the reaction chamber is connected to the electric furnace system by means of the discharging system; a gas outlet of the cyclone dust remover is connected to a dust collection system, and the dust collection system is connected to a system power source. The present invention is a production process of producing the nickel alloy with the suspension roaster-electric furnace.

Description

A device and method for smelting nickel alloy using a suspension roasting furnace-electric furnace Technical Field

The invention belongs to the technical field of laterite nickel ore smelting, and particularly relates to a device and method for smelting nickel alloy using a suspension roaster-electric furnace.

Background Art

Laterite nickel ore is a mineral formed by weathering of nickel-bearing ultrabasic rocks in tropical and subtropical regions. So far, laterite nickel ore cannot be enriched by ore dressing methods, and the raw ore can only be smelted, resulting in high investment and operating costs. The smelting of laterite nickel ore can be divided into two categories: hydrometallurgy and pyrometallurgy.

Pyrometallurgical processes include blast furnace smelting and ore-fired furnace smelting. Both processes can achieve a high nickel recovery rate of more than 90%. Blast furnace smelting includes vertical furnace and blast furnace, and it is difficult to control the reducing atmosphere during the smelting process. The vertical furnace process was used for the smelting of laterite nickel ore as early as 1875. Due to high energy consumption, high pollution and low product quality, it was eliminated globally in 1985. Due to its low investment, many factories in China revived this process between 2006 and 2010, using imported laterite nickel ore to produce low-nickel ferronickel to meet its huge market demand, but increasingly stringent environmental protection requirements and energy-saving systems have accelerated the elimination of this process. Blast furnaces are mainly used to smelt pig iron. Due to their large production capacity, complete supporting facilities and low impact on the environment, they have been transplanted to smelt nickel-iron alloys. The rotary kiln smelting process (RKEF) can produce nickel-iron with a high nickel content. The nickel content of the product can reach more than 10%, which is a good raw material for the production of stainless steel. The rotary kiln smelting process (RKEF) is considered to be a mature pyrometallurgical process. The existing laterite nickel ore smelting is mainly based on the RKEF production process. However, the RKEF process has high requirements for the quality of laterite ore and reducing agent, and is not environmentally friendly during production. It requires additional waste gas treatment equipment, which increases production costs. At the same time, the metal conversion rate of the rotary kiln material in the RKEF process is low, the coal demand is large, the power consumption is high, and the production efficiency is low.

Summary of the invention

The technical task of the present invention is to address the deficiencies of the above prior art and to provide a device and method for smelting nickel alloy using a suspension roaster-electric furnace, which is a production process for producing nickel alloy using a suspension roaster-electric furnace.

The technical solution adopted by the present invention to solve its technical problems is: a device for smelting nickel alloy using a suspension roasting furnace-electric furnace, comprising a feeding system, a magnetization roasting system, a discharging system, and an electric furnace system connected in sequence; the magnetization roasting system comprises a cyclone preheater, a suspension roasting main furnace, a cyclone separator, and a reaction chamber; the discharge port of the feeding system is connected to the feed port of the cyclone preheater, the discharge port of the cyclone preheater is connected to the air inlet at the lower end of the suspension roasting main furnace, the gas outlet of the cyclone preheater is connected to the feed port of the cyclone dust collector, and the discharge port of the cyclone dust collector is connected to the feed port at the upper end of the suspension roasting main furnace; the discharge port of the suspension roasting main furnace is connected to the feed port of the reaction chamber, and the discharge port of the reaction chamber is connected to the electric furnace system through the discharge system; the gas outlet of the cyclone dust collector is connected to the dust collection system, and the dust collection system is connected to the system power source.

Furthermore, the reaction chamber is provided with a plurality of partitions, which divide the reaction chamber into a plurality of reaction chambers; different air chambers are provided at the bottom of each reaction chamber for blowing gas into the reaction chamber to fluidize the material in the reaction chamber, and the air chambers are connected to the gas supply system respectively; the reaction chamber feed port is arranged at the top of the first reaction chamber, and the side wall of the partition is connected to the side wall of the reaction chamber, and the plurality of partitions enable the material to flow from the feed port to the discharge port in a serpentine trajectory.

Furthermore, three partitions are provided in the reaction chamber, dividing the reaction chamber into four reaction chambers, namely loosening chamber I, fluidizing chamber I, loosening chamber II, and fluidizing chamber II; the upper part of the first partition is connected to the top of the reaction chamber, the lower part of the second partition is connected to the bottom of the reaction chamber, the upper part of the third partition is not directly connected to the top of the reaction chamber, and an opening is provided between the third partition and the top of the reaction chamber, and a baffle is provided on the top of the reaction chamber in front of the opening.

Furthermore, the lower part of the second baffle is connected to the bottom of the reaction chamber, and the distance between the upper part and the top of the reaction chamber is x; the upper part of the third baffle is not directly connected to the top of the reaction chamber, and an opening with a height of y is provided between the upper part and the top of the reaction chamber; the height of the baffle is h, where y＜x＜h.

Furthermore, a metal sintered mesh is provided on the top of each air chamber, or a wind hood is provided on the top of each air chamber, and a tuyere is provided on the side of the wind hood; the gas in the air chamber enters the reaction chamber through the metal sintered mesh or the wind hood.

Furthermore, the feeding system includes a belt conveyor and an EM1 vertical mill connected in sequence; the magnetization roasting system also includes a batching machine I, and the discharge port of the batching machine I is connected to the reaction chamber; the discharge system includes an air lock valve; the electric furnace system includes an electric furnace and a batching machine II, and the discharge port of the batching machine II is connected to the electric furnace; the dust collection system includes a bag dust collector; the system power source includes a Roots blower; the smoke outlet of the bag dust collector is connected to the Roots blower, and the air outlet of the Roots blower is connected to the chimney.

Furthermore, the exhaust port of the electric furnace is connected to the main suspension roasting furnace; the exhaust port at the upper end of the main suspension roasting furnace is connected to the air inlet of the EM type vertical mill.

A method for smelting nickel alloy using the above device comprises the following steps:

Step 1: Grind the laterite nickel ore raw material to remove water to obtain laterite nickel ore powder, and send the laterite nickel ore powder to a suspension roasting system;

Step 2: The laterite nickel ore powder is preheated by a cyclone preheater and then enters the main furnace of the suspension roasting furnace for heating;

Step 3: The ore powder heated in the suspension roasting main furnace enters the reaction chamber and reacts with the reducing agent to obtain a pre-reduced material;

Step 4: introducing the pre-reduced material into an electric furnace to react therein to obtain a nickel alloy.

Furthermore, in step 1, the Fe/Ni mass content ratio in the laterite nickel ore is ≤9.

Furthermore, in step 1, the particle size of the mineral powder is less than or equal to 1.5 mm, and the moisture content is less than 10 wt %.

Furthermore, in step 2, the temperature of the cyclone preheater is 240°C-270°C, and the mineral powder is heated to 650°C-700°C in the main furnace of the suspension roasting furnace.

Furthermore, in step 2, a burner is provided at the bottom of the main furnace of the suspension roasting furnace, which is a natural gas burner or a pulverized coal injection burner.

Furthermore, in step 3, the temperature in the reaction chamber is 700-900° C., and the reaction time is 1-3 hours.

Furthermore, in step 3, the reducing agent is reducing gas or coal-based elemental carbon; if the reducing agent is coal-based elemental carbon, the ore powder is mixed with the reducing agent added by the batching machine in the front pipe of the reaction chamber, and then enters the reaction chamber, wherein the amount of coal-based elemental carbon added is 10%-15% of the mass of the ore powder; if reducing gas is used as the reducing agent, the reducing gas is directly introduced from the bottom of the reaction chamber to mix and contact with the ore powder, and the reducing gas is hydrogen and/or carbon monoxide, specifically, ^30m3 (0.2MPa) of hydrogen + ^12m3 (0.2MPa) of carbon monoxide are added per ton of laterite nickel ore, and the ore powder is fully contacted by stirring with the reducing gas.

Furthermore, in step 3, if the reducing agent is coal-based elemental carbon, nitrogen is blown into the bottom of the reaction chamber for material fluidization; if the reducing agent is reducing gas, nitrogen + reducing gas is blown into the bottom of the reaction chamber for material fluidization and reduction; the gas flow rates of different chambers are controlled by the gas supply system.

Furthermore, in step 4, the pre-reduced material is mixed with the flux material added by the batching machine in the front end pipeline of the electric furnace.

Furthermore, the composition of the nickel alloy in step 4 is controlled by blending the laterite nickel ore and/or adding the required alloy raw materials into the electric furnace.

Furthermore, in step 4, the temperature in the electric furnace is at least 1450°C.

Compared with the prior art, the present invention has the following beneficial effects:

The suspension roasting furnace in the present invention is the main stage for completing the selective reduction of nickel and achieving nickel enrichment. Before the mineral enters the suspension roasting reaction chamber, a special batching machine is used to mix an appropriate amount of reducing agent (coal-based elemental carbon) with the laterite nickel ore, or a reducing gas is directly introduced into the reaction chamber to react with the laterite nickel ore; the reducing agent completely penetrates into the surface of the dry mineral particles or the mineral phase lattice in the reaction chamber, and a reaction temperature of 700°C-900°C is selected. By accurately controlling the reaction time in the reaction chamber for 1-3 hours, the metallization rate of nickel in the laterite nickel ore reaches more than 90%, and part of the iron oxide is reduced.

The present invention smelts nickel alloy, selectively reduces nickel by accurately controlling the amount of reducing agent, and some iron oxides are not reduced. Under the high temperature conditions in the furnace, the reasonable change of raw material composition will weaken the oxidizing atmosphere, which is conducive to nickel reduction. If the Fe/Ni ratio is too high (the ratio is less than 9), the difficulty of selective reduction of nickel increases. For pre-reduced laterite ore, laterite ores of various grades and components can be used in combination to adjust the appropriate Fe/Ni ratio before entering the melting to complete the enrichment of nickel, so as to obtain a higher grade nickel alloy after melting. The present invention fully controls the reaction conditions of the suspension roasting reaction chamber, focusing on accurately controlling the reaction time, reducing agent addition ratio and temperature range of the suspension roasting reaction chamber. The ore powder discharged from the suspension roasting furnace reaction chamber is directly added to the melting by re-batch (a certain amount of flux can be added if slag making is required) to directly produce nickel alloy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a suspension roasting furnace-circuit device for smelting nickel alloy;

Fig. 2 is a schematic diagram of the reaction chamber structure;

Among them: 1. Belt conveyor; 2. EM vertical mill grinding system; 3. Cyclone preheater; 4. Suspension roasting main furnace; 5. Reaction chamber; 6. Melting furnace; 7. Air supply system; 8. Air lock valve; 9. Batching machine I; 10. Batching machine II; 11. Cyclone dust collector; 12. Bag dust collector; 13. Roots blower; 14. Chimney;
5-1. Reaction chamber inlet; 5-2. Reaction chamber outlet; 5-3. Partition plate; 5-4. Baffle plate; 5-5. Metal sintered mesh.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

Example 1

As shown in Figure 1, a device for smelting nickel alloy using a suspension roasting furnace-circuit includes a feeding system, a magnetization roasting system, a discharging system, an electric furnace system, a dust collection system, and a system power source; the feeding system includes a belt conveyor 1 and an EML vertical mill 2, the magnetization roasting system includes a cyclone preheater 3, a suspension roasting main furnace 4, a cyclone separator 11, a reaction chamber 5, and an air supply system 7; the discharging system includes an air lock valve 8; the electric furnace system includes a melting furnace 6, and the dust collection system includes a bag dust collector 12; the system power source includes a Roots blower 13.

The belt conveyor 1 responsible for transporting laterite ore is connected to the feeding port of the EM type vertical mill 2 which receives the raw ore and crushes it. The feeding port of the mill is connected to the feeding port of the cyclone preheater 3 by a stainless steel pipe. The feeding port of the cyclone preheater 3 is connected to the air inlet (material) port at the lower end of the suspension roasting main furnace 4 by a stainless steel pipe. The gas outlet of the cyclone preheater 3 is connected to the feeding port of the cyclone dust collector 11. The feeding port of the cyclone dust collector 11 is connected to the feeding port at the upper end of the suspension roasting main furnace 4 by a stainless steel pipe. The exhaust port at the upper end of the suspension roasting main furnace is connected to the air inlet of the EM type vertical mill 2 by a stainless steel pipe (to utilize the flue gas heat). A burner is arranged at the bottom of the suspension roasting furnace main furnace, which is a natural gas burner or a pulverized coal injection burner. The discharge port of furnace 4 is connected to the feed port of reaction chamber 5 by a stainless steel pipe, the gas supply system 7 is connected to the bottom of reaction chamber 5 by a stainless steel pipe, the discharge port of reaction chamber 5 is connected to air lock valve 8 by a white steel pipe, the discharge port of batching machine I9 is connected to the reaction chamber 5 by a white steel pipe, the air lock valve 8 is connected to the feed port of melting furnace 6 by a stainless steel pipe, the batching machine II10 is connected to the feed port of melting furnace 6 by a stainless steel pipe, and the exhaust port of melting furnace 6 is connected to the suspension roasting main furnace 4; the gas outlet of cyclone dust collector 11 is connected to bag dust collector 12 by a stainless steel pipe, the smoke outlet of bag dust collector 12 is connected to Roots blower 13, and the air outlet of Roots blower 13 is connected to chimney 14 by a pipe.

As shown in FIG. 2 , three partitions 5-3 are arranged in the reaction chamber, dividing the reaction chamber into four reaction chambers, namely loosening chamber I, fluidizing chamber I, loosening chamber II, and fluidizing chamber II; the side walls of the partitions are connected to the side walls of the reaction chamber, wherein the upper part of the first partition is connected to the top of the reaction chamber, and the distance between the lower part and the bottom of the reaction chamber is 200 mm, the lower part of the second partition is connected to the bottom of the reaction chamber, and the distance between the upper part and the top of the reaction chamber is 200 mm, the upper part of the third partition is not directly connected to the top of the reaction chamber, and an opening with a height of 80 mm is arranged between the upper part and the top of the reaction chamber, and the distance between the lower part and the bottom of the reaction chamber is 200 mm; A baffle 5-4 is provided at the top of the reaction chamber before the opening, and the height of the baffle is 216 mm. Different air chambers are provided at the bottom of each reaction chamber, and the air chambers are connected to the gas supply system respectively; the reaction chamber feed port 5-1 is provided at the top of the first reaction chamber, and three partitions allow the material to flow from the feed port 5-1 to the discharge port 5-2 along a serpentine trajectory. In this embodiment, part of the gas flows along a serpentine trajectory with the material, and part of the gas flows above the reaction chamber, so the third upper part is not directly connected to the top of the reaction chamber, but an opening is left. At the same time, in order to prevent the material from directly entering the next reaction chamber from the opening, a baffle is provided in front of the opening.

Wherein, a metal sintered mesh 5-5 is provided on the upper part of each gas chamber, and the gas in the gas chamber enters the reaction chamber through the metal sintered mesh or the wind cap.

Example 2

The method for smelting nickel alloy based on the device described in Example 1 comprises the following steps:

Step 1: Use a belt conveyor to deliver the raw materials to the suspension roasting system, grind the laterite nickel ore (Fe/Ni mass content ratio <9) into a -1.5 mm ore powder in an EM type vertical mill of the grinding system, and the moisture content is less than 10wt%;

Step 2: The mineral powder is preheated by the cyclone preheater and then enters the main furnace of the suspension roasting furnace for heating. The preheater temperature is 240°C, and the mineral powder is heated to 650°C in the main furnace. The bottom of the main furnace uses the hot flue gas from the electric furnace and the hot flue gas from the reaction chamber;

Step 3: The ore powder heated by the main roasting furnace enters the reaction chamber and reacts with the reducing agent therein to obtain a pre-reduced material; the reducing agent is a reducing gas, and nitrogen + reducing gas is blown into the gas chamber at the bottom of the reaction chamber for material fluidization and reduction. ^30m3 (0.2MPa) of hydrogen + ^12m3 (0.2MPa) of carbon monoxide are added to each ton of laterite nickel ore, and the ore is fully contacted by the stirring of the reducing gas; a gas lock valve is provided at the discharge port of the reaction chamber to control the reaction chamber in an anaerobic reducing atmosphere, and the mixture in the reaction chamber reacts at 700°C for 1 hour;

Step 4: The pre-reduced material is mixed with the flux material added by the batching machine in the front end pipeline of the smelting furnace, and then enters the smelting furnace to obtain the nickel alloy at 1450°C-1550°C.

Example 3

The method for smelting nickel alloy based on the device described in Example 1 comprises the following steps:

Step 1: grinding laterite nickel ore (Fe/Ni mass content ratio <9) into -1.5 mm ore powder with a moisture content of less than 10 wt% in an EM type vertical mill of a crushing and grinding system using a belt conveyor;

Step 2: The mineral powder is preheated by the cyclone preheater and then enters the main furnace of the suspension roasting furnace for heating. The preheater temperature is 270°C. The mineral powder is heated to 700°C in the main furnace. The bottom of the main furnace uses the hot flue gas from the electric furnace and the hot flue gas from the reaction chamber;

Step 3: The ore powder heated by the main furnace of the suspension roasting furnace is mixed with the reducing agent added by the batching machine in the pipeline at the front end of the reaction chamber, and then enters the reaction chamber, where it reacts with the reducing agent to obtain a pre-reduced material; nitrogen is blown into the air chamber at the bottom of the reaction chamber for material fluidization, and the reducing agent is coal-based elemental carbon, which accounts for 15% of the mass of the ore powder; a gas lock valve is provided at the discharge port of the reaction chamber to control the reaction chamber under anaerobic reduction conditions, and the mixture in the reaction chamber reacts at 900°C for 2-3 hours;

Step 4: The pre-reduced material is mixed with the flux material added by the batching machine in the front end pipeline of the smelting furnace, and then enters the smelting furnace to obtain the nickel alloy at 1450°C-1550°C.

In embodiments 1 and 2, the nickel metallization rate in laterite nickel ore reaches more than 90%. In the embodiments of the present invention, a reducing agent (coal-based elemental carbon) can be added to the pre-reduced ore powder in the front pipeline or a reducing gas ( _H2 , CO; _H2 +CO) can be introduced into the bottom of the reaction chamber to obtain a nickel alloy after melting.

The above technical scheme explains the technical idea of the present invention, which cannot be used to limit the protection scope of the present invention. Any changes and modifications made to the above technical scheme based on the technical essence of the present invention without departing from the content of the technical scheme of the present invention shall fall within the protection scope of the technical scheme of the present invention.

Claims (10)

A device for smelting nickel alloy using a suspension roasting furnace-electric furnace, characterized in that it includes a feeding system, a magnetized roasting system, a discharging system, and an electric furnace system connected in sequence; the magnetized roasting system includes a cyclone preheater, a suspension roasting main furnace, a cyclone separator, and a reaction chamber; the feeding system discharge port is connected to the cyclone preheater feed port, the cyclone preheater discharge port is connected to the lower air inlet of the suspension roasting main furnace, the cyclone preheater gas outlet is connected to the cyclone dust collector feed port, the cyclone dust collector discharge port is connected to the upper feed port of the suspension roasting main furnace; the suspension roasting main furnace discharge port is connected to the reaction chamber feed port, the reaction chamber discharge port is connected to the electric furnace system through the discharge system; the cyclone dust collector gas outlet is connected to the dust collection system, and the dust collection system is connected to the system power source. According to claim 1, a device for smelting nickel alloy using a suspension roasting furnace-electric furnace is characterized in that a plurality of partitions are provided in the reaction chamber, and the partitions divide the reaction chamber into a plurality of reaction chambers; different gas chambers are provided at the bottom of each reaction chamber for blowing gas into the reaction chamber so that the material in the reaction chamber is in a fluidized state, and the gas chambers are respectively connected to the gas supply system; the reaction chamber feed port is arranged at the top of the first reaction chamber, and the side wall of the partition is connected to the side wall of the reaction chamber, and the plurality of partitions make the material flow from the feed port to the discharge port according to a serpentine trajectory. According to claim 1, a device for smelting nickel alloy using a suspension roasting furnace-electric furnace is characterized in that three partitions are provided in the reaction chamber to divide the reaction chamber into four reaction chambers, wherein the upper part of the first partition is connected to the top of the reaction chamber, the lower part of the second partition is connected to the bottom of the reaction chamber, the upper part of the third partition is not directly connected to the top of the reaction chamber, an opening is provided between the third partition and the top of the reaction chamber, and a baffle is provided on the top of the reaction chamber in front of the opening. According to claim 1, a device for smelting nickel alloy using a suspension roasting furnace-electric furnace is characterized in that the feeding system includes a belt conveyor and an EML vertical mill connected in sequence; the magnetization roasting system also includes a batching machine I, and the discharge port of the batching machine I is connected to the reaction chamber; the discharge system includes an air lock valve; the electric furnace system includes an electric furnace and a batching machine II, and the discharge port of the batching machine II is connected to the electric furnace; the dust collection system includes a bag dust collector; the system power source includes a Roots blower; the bag dust collector smoke outlet is connected to the Roots blower, and the Roots blower outlet is connected to the chimney; The exhaust port of the electric furnace is connected to the main suspension roasting furnace; the exhaust port at the upper end of the main suspension roasting furnace is connected to the air inlet of the EM type vertical mill. A method for smelting nickel alloy based on the device according to any one of claims 1 to 4, characterized in that it comprises the following steps: Step 1: Grind the laterite nickel ore raw material to remove water to obtain laterite nickel ore powder, and send the laterite nickel ore powder to a suspension roasting system; Step 2: The laterite nickel ore powder is preheated by a cyclone preheater and then enters the main furnace of the suspension roasting furnace for heating; Step 3: The ore powder heated in the suspension roasting main furnace enters the reaction chamber and reacts with the reducing agent to obtain a pre-reduced material; Step 4: introducing the pre-reduced material into an electric furnace to react therein to obtain a nickel alloy. The method for smelting nickel alloy according to claim 5, characterized in that in the step 1, the Fe/Ni mass content ratio in the laterite nickel ore is ≤9; the particle size of the ore powder is less than or equal to 1.5 mm, and the moisture content is less than 10 wt%. The method for smelting nickel alloy according to claim 5 is characterized in that in the step 2, the temperature of the cyclone preheater is 240°C-270°C, and the ore powder is heated to 650°C-700°C in the main furnace of the suspension roasting furnace; in the step 4, the temperature in the electric furnace is at least 1450°C. The method for smelting nickel alloy according to claim 5, characterized in that in step 3, the temperature in the reaction chamber is 700-900° C. and the reaction time is 1-3 hours. The method for smelting nickel alloy according to claim 5 is characterized in that the reducing agent is reducing gas or coal-based elemental carbon; if the reducing agent is coal-based elemental carbon, the mineral powder is mixed with the reducing agent added by the batching machine in the front end pipeline of the reaction chamber, and then enters the reaction chamber, wherein the amount of coal-based elemental carbon added is 10%-15% of the mass of the mineral powder; if reducing gas is used as the reducing agent, the reducing gas is hydrogen and/or carbon monoxide, and the reducing gas is directly introduced from the bottom of the reaction chamber to mix and contact with the mineral powder. The method for smelting nickel alloy according to claim 5 is characterized in that the composition of the nickel alloy in step 4 is controlled by blending laterite nickel ore and/or adding the required alloy raw materials into the electric furnace.