CN113684362A

CN113684362A - Device and method for optimizing low-grade laterite-nickel ore through gas-based direct reduction and magnetic separation

Info

Publication number: CN113684362A
Application number: CN202110865840.4A
Authority: CN
Inventors: 张雷; 张凯玮; 张妍琪
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-07-29
Filing date: 2021-07-29
Publication date: 2021-11-23

Abstract

The invention relates to the technical field of energy-saving comprehensive utilization of mineral resources, in particular to a device and a method for optimizing low-grade laterite-nickel ore by gas-based direct reduction and magnetic separation; the device comprises a kiln body, wherein a roundabout snake-shaped flue is arranged in the kiln body from top to bottom, and the snake-shaped flue is divided into a roasting preheating section, a roasting heating section and a roasting reduction section from top to bottom; a preheating material pool is arranged above the roasting preheating section, the bottom of the roasting preheating section is communicated with a vertical blanking channel, and the blanking channel passes through the roasting heating section and the roasting reduction section and is isolated from the roasting heating section and the roasting reduction section; the bottom end of the blanking channel is communicated with an air cooling pipe, and the bottom of the air cooling pipe is connected with a material output device and a grinding magnetic separation system; the method comprises the steps of processing raw materials, directly reducing and roasting in a gas base manner, grinding and magnetic separation optimizing to obtain a final optimized product; the invention solves the problems of low reduction efficiency, long reduction heating time, high heating temperature and poor heat preservation effect in the prior art.

Description

Device and method for optimizing low-grade laterite-nickel ore through gas-based direct reduction and magnetic separation

Technical Field

The invention belongs to the technical field of energy-saving comprehensive utilization and direct reduction of mineral resources, and relates to a gas-based direct reduction roasting kiln and a mineral optimization method; in particular to a device and a method for optimizing low-grade laterite-nickel ore by gas-based direct reduction and magnetic separation.

Background

The nickel has the characteristics of strong corrosion resistance, good heat resistance and the like, and is widely applied to various fields such as stainless steel, special alloy steel and the like; at present, 60% of nickel metal in the world is extracted from nickel sulfide ore, the production process is mature, but the nickel sulfide ore resource is reduced day by day, the demand of nickel is increased day by day with the rapid development of the stainless steel industry, and the development and utilization of the laterite nickel oxide ore occupying 70% of the nickel resource reserve of the earth ball have very important practical significance.

The traditional process for treating nickel oxide ore is pyrometallurgical ferronickel alloy, the process mainly treats metamorphic olivine with higher nickel grade, and is divided into rotary kiln prereduction and shaft furnace reduction-ore-smelting electric furnace-refining method according to the difference of reduction processes, but the rotary kiln prereduction and the shaft furnace reduction have no direct and sufficient reduction atmosphere required by laterite-nickel ore because smoke dilutes reduction gas, and both of the rotary kiln prereduction and the shaft furnace reduction increase the temperature and reduce, thus causing the problems of difficult control of thermal engineering, high-temperature bonding agglomeration, high energy consumption, low production efficiency, unstable production and the like; the recovery rate of nickel and the grade of nickel alloy are not high; so that the industrial production application of the gas-based shaft furnace process is frequently frustrated.

Disclosure of Invention

The invention overcomes the defects of the prior art and provides a device and a method for optimizing low-grade laterite-nickel ore by gas-based direct reduction and magnetic separation.

In order to achieve the above object, the present invention is achieved by the following technical solutions.

The utility model provides a device of low-grade laterite-nickel ore deposit is optimized in gas base direct reduction magnetic separation, includes the kiln body, the internal snakelike flue that is provided with circuitous from top to bottom of kiln, snakelike flue from the top down divide into the three-layer, does in proper order: a roasting preheating section, a roasting heating section and a roasting reduction section; the roasting preheating section is connected with a flue gas collecting and air inducing device, a preheating material pool is arranged above the roasting preheating section, the preheating material pool is communicated with the roasting preheating section through a preheating material pipe, the bottom of the roasting preheating section is communicated with a vertical blanking channel, and the blanking channel penetrates through and is isolated from the roasting heating section and the roasting reduction section; the roasting reduction section is connected with a burner of a combustion chamber; the roasting heating temperature in the roasting reduction section is 960-1030 ℃; the bottom end of the blanking channel is communicated with an air cooling pipe for cooling materials, and a reducing gas preheating and reducing device is arranged in the air cooling pipe; the reducing gas preheating and reducing device is communicated with a reducing gas pipeline; the pressure of the reducing gas is 600-1200 Pa; the bottom of the air cooling pipe is connected with a material output device, and the material output device is sequentially connected with a pair roller circulating grinding system, a Raymond circulating grinding system and a magnetic separation optimization system.

Further, a reducing gas outlet of the reducing gas preheating and reducing device is arranged at the upper end in the air cooling pipe and faces the blanking channel; the heat preservation structure is wrapped above the middle part of the air cooling pipe.

Further, an air inlet preheater is arranged outside the air cooling pipe, an outlet of the cooling hot air collector is connected with an inlet of the air inlet preheater, and the air inlet preheater is connected with a fire nozzle of the combustion chamber.

Further, the material is cooled to 45-55 ℃ after passing through an air cooling pipe.

The system further comprises a raw material processing system, wherein the raw material processing system comprises a nickel ore screening granulator, a flue gas purification dryer and a nickel ore screening output device which are sequentially connected, and the nickel ore screening output device is connected with the preheating material pool; the smoke collection and air induction device is connected with the smoke purification dryer.

Further, the pair-roller circulating grinding system comprises a pair-roller mill, a screening and extracting device and a lifter which are sequentially connected; the Raymond circulating grinding system comprises a Raymond mill, a thickness separating device and a centrifugal pumping device which are sequentially connected; the magnetic separation system comprises a medium magnetic separator, a strong magnetic selection device and a medium magnetic selection device which are sequentially connected.

Furthermore, the screening and pumping device and the medium-magnetic separator are respectively connected with the ash and dust removing device.

Further, the kiln body is hollow shell, and kiln body roof middle part is equipped with the preheating material pond to the internal side of kiln with caving in, and preheating material pond top is equipped with the cloth machine, and the terminal below of forced air cooling pipe is equipped with the guide impeller, and guide impeller below is equipped with the guide platform, guide platform below is equipped with the feed bin, and the feed bin below is equipped with output hoisting device.

Furthermore, a supporting beam is arranged between the lower part of the flue and the bottom surface of the kiln body, a backing ring is arranged below the bottom surface of the kiln body, and a supporting column is arranged between the backing ring and the ground.

Further, the bottom surface of the preheating distribution tank is made of a steel plate.

Further, the preheating pipe is a square steel pipe.

Furthermore, the heating chamber and the burner are connected to the lower end of the serpentine flue, a fire observation hole is formed in the side wall of the heating chamber, and a temperature monitoring device is arranged on the side wall of the heating chamber above the fire observation hole.

Furthermore, a partition plate is arranged between the roasting heating section and the roasting preheating section, and flanges are symmetrically arranged in the roasting heating section and the roasting preheating section at the tail end of the partition plate.

Furthermore, a partition plate is arranged between the roasting reduction section and the roasting heating section, and a flange is arranged at the tail end of the partition plate towards the roasting reduction section.

Furthermore, the side wall of the roasting reduction section is provided with a gas overflow port after reduction of the reduction section.

Further, the reduced gas overflow port is communicated with the roasting reduction section.

Furthermore, a temperature monitoring device is arranged through the side wall of the roasting reduction section and the side wall of the kiln body.

Further, communicated heat-preservation sealing gaps are arranged between the side wall of the kiln body and the preheating distribution tank and between the side wall of the kiln body and the roasting system.

A method for optimizing low-grade laterite-nickel ore by gas-based direct reduction and magnetic separation comprises the following steps:

a) raw material treatment: screening, granulating, drying and screening the low-grade laterite-nickel ore to obtain laterite-nickel ore particle materials with the particle size of 3-40mm, wherein the weight percentage of water is less than 10%.

b) Gas-based direct reduction roasting: when the smoke temperature of the roasting reduction section reaches 900-; meanwhile, reducing gas is introduced into the blanking channel, and when the flue gas temperature of the roasting reduction section reaches 980 ℃, the blanking speed is v 2; v2 is 5-6 times of v 1; tiling and stacking the low-grade laterite-nickel ore particle material in a preheating material pool to achieve a thickness of 200-300 mm; the rising speed of the flue gas temperature in the roasting reduction section is less than or equal to 2 ℃/min.

c) And feeding the laterite nickel ore particle material subjected to gas-based direct reduction roasting into an air cooling pipe.

d) The cooled materials enter a double-roller circulating grinding system to obtain separated materials of more than 200 meshes, and then the separated materials of more than 300 meshes are obtained through a Raymond circulating grinding system; and then obtaining a nickel alloy product through a magnetic separation system, wherein the mass percentage of nickel in the nickel alloy product is Ni > 8%.

Preferably, the laterite nickel ore particle material is fed under the control of a material guide impeller, and the rotating speed of the material guide impeller is 4-6 r/h.

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

1) for the raw material treatment: the raw materials are heated and dried by using the residual heat of the flue gas of the gas-based direct reduction roasting kiln, the smoke discharge temperature of the roasting kiln is 160-200 ℃, the cooling hot air of the roasting material is used as a standby heat source, the raw materials are heated and dried, the production is convenient, and the following favorable conditions are provided for the gas-based direct reduction roasting.

The method comprises the following steps of introducing hot flue gas into a drying device, enabling the flue gas to flow through gaps of raw material particles, enabling micro-dust and harmful substances in the flue gas to be bonded and adsorbed by the raw material particles, incidentally pumping ash to remove the micro-dust and the harmful substances in the screening process, enabling the raw material particles to become flue gas purification filler, enabling the flue gas to be purified and environment-friendly, enabling the temperature of the purified flue gas to be lower than 60 ℃, reducing environmental protection investment, drying the raw material, obviously improving the utilization efficiency of the waste heat of the flue gas, and screening to obtain particle materials.

Secondly, the nickel ore screening is adopted to directly remove part of impurities (6-10%) in the laterite-nickel ore by dust extraction, the roasting and heating energy consumption is reduced by more than 6%, and the production process is environment-friendly.

The reduction contact area of nickel ore particle gaps is increased, the capacity and the retention space of reducing gas are sufficient, and the reaction time is sufficient;

the gaps of the particles are convenient for the roasting material to absorb the heat energy of the flue gas and evaporate water quickly and discharge the water along with the flue gas in time, and the consumption of roasting and heating natural gas is obviously reduced.

The particle gaps are favorable for reduction reaction, the gas naturally ascends after reduction and escapes in time, and the concentration of the reduction gas is increased in time.

The gaps of the particles are beneficial to the gas after reduction and the excess reducing gas to overflow into the serpentine flue at the reduction section, so that the excess reducing gas and the excess air can be timely and fully combusted in the serpentine flue, and the utilization efficiency of the circulating heat energy is improved; and is also beneficial to the natural formation of gas-based full convection reduction reaction in the blanking channel.

2) For the gas-based direct reduction roasting process: the gas-based direct reduction roasting has the advantages that roasting heating flue gas and blanking reduction are performed in a separate way, so that the situation that the concentration of the reducing gas is insufficient due to dilution of the reducing gas by the flue gas is avoided, the roasting heating combustion is sufficient, and the concentration of the blanking reducing gas is sufficient and excessive is avoided. Blanking particle gaps: the contact surface of reducing gas is enlarged, the holding space is sufficient, the reaction time is sufficient, and the frequency conversion of the reducing time is adjustable.

The preheating device preheats the reducing gas, the preheating air supply temperature is higher than 320 ℃, the heat energy loss in the roasting process is obviously reduced, the cooling efficiency of the roasting material is improved, and the heat energy recycling efficiency is obviously improved. The gas-based direct reduction roasting is carried out, the reduction temperature is controlled at 930 +/-30 ℃, the reduction is carried out at the low temperature, the exhaust gas temperature of the gas-based direct reduction roasting kiln is 160-200 ℃, the raw material is heated and dried by using the waste heat of the flue gas, the temperature of the exhaust gas after heating and drying is less than 60 ℃, and the loss of the exhaust heat energy is obviously reduced. The gas-based direct reduction roasting kiln has good heat preservation effect, the external temperature of the kiln is close to normal temperature, and the heat dissipation loss is greatly reduced. The gas-based direct reduction roasting kiln heats the flue gas up along the serpentine flue layer by layer in a natural heating way, so that the power consumption of flue gas induced air is very low. The roasting material is under the gravity, so the power consumption of blanking is controlled to be extremely low.

In the roasting reduction process, gas-based reduction gas enters the air cooling pipe from the middle upper part of the cooling pipe, the reduction gas naturally and slowly ascends along with the preheating reduction of roasting particle gaps, and gas-based convection reduction reaction is naturally formed in the blanking channel; and the reduced gas and the excessive reducing gas overflow into the serpentine flue from the overflow port. Overflowing the excessive reducing gas into a snake-shaped flue: the excess reducing gas and the excess air in the serpentine flue are timely and fully combusted, the investment and the cost of flue gas treatment equipment are saved, the energy-saving efficiency of flue gas heat energy recycling is obviously improved, the energy consumption of roasting and heating is obviously reduced, the flue gas emission is reduced, and the environment is protected.

The air supply is preheated by utilizing the cooling heat energy of the roasting material, the self heat absorption energy consumption of the air supply is reduced, the cooling heat energy of the roasting material is recycled, and the consumption of heating natural gas is obviously reduced. The two side walls of the snakelike flue are heated to store heat and energy uniformly, the smoke containing space of the snakelike flue is large, and the instantaneous heating temperature is too high, so that the heat can be timely and fully relieved.

The roasting heating flue gas slowly goes upwards from the lower layer-by-layer snake-shaped natural heating along the reduction section snake-shaped flue, the heating section snake-shaped flue and the preheating section snake-shaped flue, and the heat exchange efficiency is obviously improved. The roasting material falls into the blanking channel of the preheating section, the roasting material is in direct contact with the heating flue gas, the roasting material fully absorbs the heat energy of the flue gas, and the moisture is quickly evaporated and discharged along with the flue gas in time.

The roasting material falls into the material falling channel of the reduction section, the reduced gas and the excess reducing gas overflow into the serpentine flue from the overflow port of the reduction section, the excess reducing gas and the excess air in the serpentine flue are timely and fully combusted, the environment-friendly investment is reduced, the pollution emission is reduced, the excess air is timely and adjustable by utilizing the preheated hot air, and the timely cyclic utilization efficiency of heat energy is obviously improved.

The roasting material falls into a material falling channel of the roasting heat-preservation connecting section, the reduction temperature is kept well, the concentration of the reduction gas is sufficient, the reduction time is sufficient, and the roasting convection reduction atmosphere is more sufficient and reliable. The roasting material falls into the air cooling pipe, the roasting material is cooled and slowly descends under the control of the rotating speed of the material guide impeller of 4-6 revolutions per hour, and the power consumption of the rotating power of the material guide impeller is extremely low; the roasting material is naturally air-cooled to about 50 ℃ in the air-cooled pipe, so that the secondary oxidation of the roasting material is avoided, no water is used for magnetic separation optimization, the water resource consumption is saved, and the regional adaptability is strong.

The method comprises the following steps of (1) gas-based direct reduction roasting, wherein a partition plate is arranged between a roasting reduction section and a roasting heating section in a flue, and a flange is arranged at the tail end of the partition plate towards the roasting reduction section; the partition plate is arranged between the roasting heating section and the roasting preheating section, and flanges are symmetrically arranged in the roasting heating section at the tail end of the partition plate and the roasting preheating section, so that the temperature of each section is effectively guaranteed.

The gas-based direct reduction roasting has the advantages that the temperature, the concentration of the reduction gas and the reduction time required in the reduction roasting process are respectively controlled, the mutual influence among various control parameters is relatively weak, the high-degree natural coordination control can be realized, the nickel ore is carried out in the required full convection reduction atmosphere, and the thermal control is accurate and easy to control. The gas-based direct reduction roasting process has the advantages that internal and external preheating and heating are carried out in the process of gas-based direct reduction roasting, heat energy is recycled, the consumption of roasting and heating natural gas is obviously reduced, and the problems of low reduction efficiency, long reduction and heating time, high heating temperature and poor heat preservation effect in the prior art are solved; because the reduction temperature is controlled at 930 +/-30 ℃ for low-temperature reduction, the roasted material is extremely easy to be ground, and convenience is provided for further magnetic separation optimization.

3) A pair-roller circulating grinding system: because nickel in the reducing material mainly exists in a metal iron-nickel eutectic form, the granularity is generally below 10 mu m, the laterite-nickel ore is reduced at low temperature of 930 +/-30 ℃, the reducing material is extremely easy to grind and the impurities are extremely easy to separate, the obtained reducing material is ground to be more than 200 meshes through a double-roll mill, a screening and extracting device, a lifter and circulating grinding in sequence, most of impurity dust is timely removed through dust extraction, and the reducing material with the particle size of more than 200 meshes is obtained.

4) Ramon cycle grinding system: and (3) circularly grinding, ash pumping and dust removing the 200-mesh reduced material by a Raymond mill, a coarse-fine separation device and a centrifugal pumping device in sequence to obtain 300-mesh reduced material, wherein each ton of the reduced material is ground to 300-mesh ore with the power consumption of less than 50 degrees per ton of ore.

5) Magnetic separation optimizing system: the separated material with the granularity of more than 300 meshes is sequentially subjected to a medium magnetic separator, a strong magnetic concentration device and a medium magnetic concentration device, the reduced iron fine powder is optimally extracted, the non-magnetic heavy metal is separated and recovered, the grade of the residual nickel alloy is obviously improved, and an optimized nickel alloy product is obtained; solves the problems of low grade, high energy consumption and difficult recovery of the laterite-nickel ore, and provides high-quality and high-price raw materials for the electrolytic nickel enterprises.

6) Ash and dust removing separation system: because the impurities in the laterite-nickel ore are relatively soft and have relatively small specific gravity compared with metal materials such as iron-nickel eutectic, reduced iron and the like, and secondly, after the laterite-nickel ore is directly reduced and roasted by gas base, the reduced materials are extremely easy to grind, the impurity dust is directly removed by dust extraction, the negative pressure of the dust extraction and removal system provides negative pressure convenience for the magnetic separation optimization process, and the dust removal efficiency is further improved by electrostatic dust removal.

7) Flue gas waste heat utilization system: the flue gas waste heat utilization system is the flue gas induced air collection device, and the flue gas induced air collection device introduces flue gas into the flue gas purification drying device, so that the flue gas purification environment-friendly investment is reduced, the raw materials are dried, the waste heat is utilized, and the emission is reduced, so that the environment is protected.

The device is suitable for treating any type of nickel oxide ore, is particularly suitable for optimizing difficult ore dressing and composite ores, generally requires that the iron content Fe of low-grade laterite nickel ore is more than 38%, the higher the iron grade is, the better the benefit is, various types of nickel oxide ore can be mixed and roasted, the magnetic separation optimization does not influence the recovery rate of nickel, the recovery rate of nickel is more than 95%, the effect of removing harmful impurities is obvious, the sulfur removal efficiency is more than 60%, and the phosphorus removal efficiency is more than 65%.

Compared with other existing processes at home and abroad, the process flow is short, flexible, practical, energy-saving and efficient, the nickel is not adhered and agglomerated, the recovery rate of nickel is high, the treatment capacity is large, the product quality is stable, the relative investment is small, the effect is quick, the intensive large-scale production can be realized while the production is carried out, and the rolling explosive type growth development can be realized; therefore, the process is a new clean energy-saving direct reduction process with high quality, low consumption, energy conservation and high efficiency, has wide market development prospect, is easy to popularize, has huge energy-saving development potential because the comprehensive energy consumption is less than one half of that of other processes, and has more advantages in energy conservation and emission reduction from the source.

Drawings

FIG. 1 is a main sectional view showing the structure of a gas-based direct reduction roasting kiln of the present invention.

FIG. 2 is a schematic sectional view taken along the plane A-A in FIG. 1.

Fig. 3 is a schematic connection diagram of the device for optimizing the low-grade laterite-nickel ore by gas-based direct reduction magnetic separation.

In the figure: the device comprises a kiln body 1, a preheating material pool 2, a preheating material pipe 3, a blanking channel 4, a roasting preheating section 5, a roasting heating section 6, a roasting reduction section 7, a heat preservation reduction connecting section 8, a reducing gas preheating reduction device 9, an air cooling pipe 10, a guide impeller 11, a guide platform 12, a storage bin 13, an output lifting device 14, a heat preservation sealing gap 15, an air supply preheater 16, a cooling hot air collector 17, a support beam 18, a backing ring 19, a support column 20, a distributing machine 21, a serpentine flue 22, a temperature monitoring device 23, a fire observation hole 24, a combustion chamber 25 and a reduced gas overflow port 26.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solutions of the present invention are described in detail below with reference to the embodiments and the drawings, but the scope of protection is not limited thereto.

As shown in fig. 3, a device for optimizing low-grade laterite-nickel ore by gas-based direct reduction and magnetic separation mainly comprises 7 parts: the device comprises a raw material processing system, a gas-based direct reduction roasting kiln, a pair-roller circulating grinding system, a Raymond circulating grinding system, a magnetic separation optimizing system, an ash and dust removing system and a flue gas waste heat utilization system.

The raw material processing system comprises a nickel ore screening granulator 101, a flue gas purification and drying device 102 and a nickel ore screening and outputting device 103 which are connected in sequence.

Gas-based direct reduction roasting kiln: as shown in fig. 1-2, wherein: kiln body 1 is hollow shell, and the internal brickwork of kiln 1 from top to bottom has circuitous snakelike flue 22, and the heating of the wide 24 centimetre both sides walls of snakelike flue is even, and snakelike flue from the top down divide into the three-layer, does in proper order: the device comprises a roasting preheating section 5, a roasting heating section 6 and a roasting reduction section 7, wherein a preheating material pool 2 is concavely arranged in the middle of the top wall of a kiln body 1 towards the inner side of the kiln body 1, a distributing machine 21 is arranged above the preheating material pool 2, and materials passing through a raw material processing system are conveyed to the preheating material pool 2 through the distributing machine 21; a plurality of preheating pipes 3 are uniformly arranged on the bottom surface of the preheating material pool 2, the preheating material pool 2 is communicated with a roasting preheating section 5 through the preheating pipes 3, the bottom of the roasting preheating section 5 is communicated with a vertical blanking channel 4, and the blanking channel 4 penetrates through a roasting heating section 6 and a roasting reduction section 7 and is isolated from the roasting heating section 6 and the roasting reduction section 7; the bottom end of the blanking channel 4 is communicated with an air cooling pipe 10 used for cooling materials, and the middle upper part of the air cooling pipe 10 is provided with a reducing gas preheating and reducing device 9 and communicated with a reducing gas pipeline; the reducing gas outlet of the reducing gas preheating and reducing device 9 is arranged at the upper end in the air cooling pipe 10 and faces the blanking channel 4, and the reducing gas preheating and reducing device 9 provides reducing gas for the blanking channel 4.

The air supply preheater 16 is arranged on the outer wall of the air cooling pipe 10, a hot air outlet is connected with the combustion chamber 25 to provide preheated air for the combustion chamber 25, and a cooling hot air collector 17 is further arranged on the outer wall of the air cooling pipe 10. The cooling hot air collector 17 is connected with the air supply preheater 16, and the side wall of the upper part of the blanking channel 4 at the roasting reduction section 7 is uniformly provided with a reduced gas overflow port 26. The roasting reduction section 7 is connected with a burner of a combustion chamber 25. The side wall of the roasting reduction section 7 is provided with a fire observation hole 24, and a temperature monitoring device 23 is arranged above the fire observation hole 24.

And a partition plate is arranged between the roasting reduction section 7 and the roasting heating section 6, and a flange is arranged at the tail end of the partition plate towards the roasting reduction section 7. And a partition plate is arranged between the roasting heating section 6 and the roasting preheating section 5, and flanges are symmetrically arranged in the roasting heating section 6 and the roasting preheating section 5 at the tail end of the partition plate. And communicated heat-preservation sealing gaps 15 are arranged between the side wall of the kiln body 1 and the preheating material pool 2 and between the side wall of the kiln body 1 and the roasting system. A heat-preservation reduction connecting section 8 is supported below the roasting reduction section 7, a supporting beam 18 is arranged between the lower part of the heat-preservation reduction connecting section 8 and the bottom surface of the kiln body 1, a backing ring 19 is arranged below the bottom surface of the kiln body 1, and a supporting column 20 is arranged between the backing ring 19 and the ground.

A material guiding impeller 11 is arranged below the tail end of the air cooling pipe 10, a material guiding platform 12 is arranged below the material guiding impeller 11, a storage bin 13 is arranged below the material guiding platform 12, and an output lifting device 14 is arranged below the storage bin 13.

The material sent out from the kiln body 1 is sent to a double-roller circulating grinding system by an output lifting device 14: the paired roller circulating grinding system comprises a paired roller mill 301, a screening and extracting device 302 and a lifting machine 303 which are connected in sequence. Then entering a Raymond circular grinding system: the device comprises a Raymond mill 401, a coarse-fine separation device 402 and a centrifugal pumping device 403 which are connected in sequence. Then entering a magnetic separation optimization system: the magnetic separation optimization system comprises a middle magnetic separator 501, a strong magnetic separation device 502 and a middle magnetic separation device 503 which are sequentially connected, and finally, an optimized nickel alloy 504, nonmagnetic heavy metal 505 and optimized fine iron powder 506 are separated.

The ash removing and dust removing system comprises an ash removing and dust removing device 601 and an electrostatic dust removing device 602. The flue gas waste heat utilization system is a flue gas induced air collecting device 701.

The gas-based direct reduction roasting kiln flue gas waste heat is connected with the flue gas induced air collecting device 701 through a heat source pipeline; an output port of the nickel ore screening and outputting device 103 is connected with a feeding port of a distributing machine 21 of the gas-based direct reduction roasting kiln; an outlet of an output lifting device 14 of the gas-based direct reduction roasting kiln is connected with a feeding port of the double-roller mill 301; the discharge port of the screening and extracting device 302 is connected with the feeding port of the Raymond mill 401; the centrifugal pumping device 403 is connected with the middle magnetic separator 501.

The ash and dust removing system is respectively connected with the pair-roller circulating grinding system, the Ramon circulating grinding system and the magnetic separation optimization system. The flue gas induced air collecting device 701 is connected with the flue gas purifying and drying device 102.

1) a raw material processing system: comprises a nickel ore screening granulator 101, a flue gas purification and drying device 102 and a nickel ore screening and outputting device 103 which are connected in sequence.

Nickel ore screening granulator 101: screening and granulating the laterite-nickel ore to prepare for drying.

Flue gas cleaning and drying device 102: gas-based direct reduction roasting kiln flue gas waste heat is utilized, the flue gas temperature is 160-200 ℃, and roasting material cooling hot air is used as a standby heat source; the heated flue gas is introduced into the flue gas purification and drying device 102 to heat and dry the raw materials, the flue gas flows through gaps of raw material particles, the micro-dust and harmful substances in the flue gas are bonded and adsorbed by the nickel ore particles, and the flue gas is purified and the environmental protection investment is reduced; the nickel ore particles become the flue gas purification filler to be dried, and tiny dust and harmful substances are removed by way of dust extraction in the screening process; the smoke discharging temperature after the smoke purification is less than 60 ℃, the waste heat loss of the smoke is reduced, and the utilization efficiency of the waste heat of the smoke is obviously improved; heating and drying to make the weight percentage of the water content of the raw and auxiliary material particles less than 10%.

Nickel ore screening output device 103: the method comprises the steps of crushing and screening the dried nickel ore to obtain nickel ore particles with the particle size of 3-40mm, removing impurity dust in the powder ore with the particle size of less than 3 mm by means of dust extraction, reducing roasting and heating energy consumption, returning the dried powder ore to pelletize again to facilitate pelletization production, and enabling the production process to be environment-friendly, wherein the nickel ore particles with the particle size of 3-40mm are obtained and are input into a feeding port of a roasting kiln distributing machine 21 through a nickel ore screening and outputting device 103.

2) Gas-based direct reduction roasting:

filling nickel ore particle materials of 3-40mm into a discharging channel 4 of a roasting kiln through a distributing machine 21, and tiling and stacking the nickel ore particle materials in a preheating material pool 2 to achieve the thickness of 200-300 mm; the heating and temperature rising speed of a burner of the combustion chamber 25 is started to be less than or equal to 2 ℃/min, the temperature of each section in the serpentine flue is monitored by the temperature monitoring device 23, when the flue gas temperature of the reduction section flue reaches 900 ℃, the material guide impeller 11 is slowly opened to start feeding at 1 r/h, the regulating main valve of the reducing gas preheating device is slowly opened to start gas supply, the gas pressure of the reducing gas is quickly regulated to the full reduction range required by the roasting material along with the temperature rise, and the gas pressure regulating range is as follows: the air pressure of the reducing gas is higher than the marked air pressure of 600-1200 Pa; reducing gas enters the blanking channel 4 through a reducing gas preheating and reducing device 9, the temperature rises along with the reduction temperature of the roasting material, when the temperature of the snakelike flue of the reduction section rises to 980 ℃, the blanking speed is adjusted to about 5 revolutions per hour.

The roasting material falls into a preheating section: the heating flue gas of the roasting preheating section 5 and the reduction blanking are in the same space, so that the roasting material can fully absorb the heat energy of the flue gas, the moisture is quickly evaporated and discharged along with the flue gas, and the flue gas temperature is 160-200 ℃.

The roasted material falls into the heating section: the heating section blanking channel 4 is separated from the roasting heating section 6, and the roasted material is slowly heated downwards along with the material guiding rotation speed.

The calcine falls into the reduction stage: the reduction section blanking channel 4 is separated from the roasting reduction section 7, so that the dilution of the reducing gas by the flue gas is avoided, the reducing gas flows upward along with the convective reduction heating of gaps of roasting material particles, the reduced gas and the excess reducing gas overflow into the serpentine flue from the overflow port, the excess reducing gas and the excess air in the serpentine flue are timely and fully combusted, the excess reducing gas treatment equipment is omitted, the cost and the environment are friendly, the energy-saving recycling efficiency of the excess reducing gas is obviously improved, and the concentration of the reducing gas can be timely adjusted according to the requirement of full reduction on air pressure. The two side walls of the serpentine flue with the width of 24 cm of the reduction section are heated to uniformly store heat and energy, and the over-high instantaneous temperature can be relieved in time; the heating smoke slowly and naturally goes upwards to heat layer by layer along with the serpentine flue; the heating and combustion is sufficient, the heating temperature is adjustable by utilizing preheating and air supply, the reduction temperature is controlled to be 930 +/-30 ℃, the speed of the roasted material naturally falls along with the rotating speed of a guide impeller, the speed is adjustable, and the convection reduction time is sufficient.

The roasting material falls into a heat-preservation reduction connecting section: the reduction temperature is kept well, the reduction gas is sufficient, the roasted material passes through the reduction section and the heat preservation section for more than 6 hours at 5 revolutions per hour, the reduction time required by the roasted material is less than 3 hours, the reduction time is sufficient, and the roasting convection reduction atmosphere is sufficient.

Reducing gas enters the blanking pipeline 4 from the middle upper part of the air cooling pipe 10, the reducing gas is slowly preheated along with the gaps of the particles, is reduced and ascends, and gas-based convection reduction reaction is naturally formed in the blanking channel.

The roasting material falls into the air cooling pipe 10, natural air cooling avoids reoxidation risk, the temperature of hot air is further improved by utilizing the cooling heat energy of the roasting material, and the temperature of preheating air supply is generally 320-380 ℃, so that the heat absorption energy consumption of the hot air is obviously reduced, experiments show that the consumption of heating natural gas is relatively reduced by more than 18%, the roasting material is cooled to about 50 ℃, the cooling efficiency is improved, and the heat energy recycling efficiency in the roasting reduction process is obviously improved.

After air cooling, the roasting material passes through the material guide platform 12 and falls into the roasting bin 13 under the control of the material guide impeller 11. The roasted material is input into the double-roller circular grinding system through the output lifting device 14. The gas-based direct reduction roasting not only forms a sufficient and efficient convection reduction reaction, but also ensures that the low-temperature reduction roasting material is extremely easy to mill and separate impurities, and provides convenience for further magnetic separation optimization.

3) A pair-roller circulating grinding system: double roll mill 301 double roll mill circulation milling reduces the reducing material to above 200 mesh. Screening extraction device 302: circulating screening and pumping to separate reducing materials with more than 200 meshes in time. The hoisting machine 303: the hoister 303 circularly hoists to facilitate the circular grinding and ash pumping production.

4) Ramon cycle grinding system: raymond mill 401: grinding the reduced material with more than 200 meshes to more than 300 meshes by a Raymond mill in a circulating way. A thickness separator 402: the <300 mesh reduced material was separated and returned to the recycle mill. Centrifugal extractor 403: and (5) timely extracting the reducing material with the granularity of more than 300 meshes.

5) Magnetic separation optimizing system: the medium magnetic separator 501: and (3) performing magnetic separation on the obtained separated material with the granularity of more than 300 meshes by using a medium magnetic separator to optimally extract the reduced iron powder, so that the nickel grade of the obtained residual nickel alloy material is obviously improved. Strong magnetic concentration device 502: and carrying out strong magnetic concentration on the obtained residual nickel alloy material, and separating non-magnetic heavy metals to obtain an optimized nickel alloy product. The medium magnetic concentration device 503: and (3) carrying out medium magnetic concentration on the optimally extracted reduced iron powder to obtain optimized fine iron powder 506.

And packaging and warehousing the optimized nickel alloy products after the products are inspected to be qualified. And packaging and warehousing the non-magnetic heavy metals after the non-magnetic heavy metals are inspected to be qualified. And packaging or briquetting and warehousing the optimized reduced iron fine powder product after the product is inspected to be qualified.

6) Ash and dust removing system: negative pressure ash-removing dust-removing device 601: the ash removal and dust removal system not only removes ash and dust but also provides system negative pressure for the magnetic separation optimization process. Electrostatic precipitator 602: the electrostatic dust collection further improves the dust collection efficiency.

7) The flue gas induced air collecting device 701 collects the flue gas generated by the gas-based direct reduction roasting, and introduces the flue gas into a flue gas purification and drying device to heat and dry the raw materials.

Example 1

0.85 percent of certain low-grade laterite-nickel ore Ni0.17 percent and Fe49.17 percent. The method comprises the following steps:

firstly, raw material treatment: screening, granulating, drying and screening raw materials of 0.85% of Ni0.85% and Fe49.17% of laterite-nickel ore to obtain nickel ore particles with the particle size of 3-40mm, wherein the weight percentage of water is less than 10%;

② gas-based direct reduction roasting: roasting the 3-40mm particle nickel ore material in a gas-based direct reduction roasting test kiln, controlling the gas pressure of gas-based reduction gas to be 600-1200Pa higher than the marked gas pressure, controlling the reduction temperature of a reduction section to be about 930 ℃, and discharging at the rotating speed of a guide impeller of 5 r/h to obtain a roasting reduction material.

③ grinding by double rollers: and (3) grinding the obtained reduced material to be more than 200 meshes by a pair of roller mills, a screening and extracting device, a lifter and circulating grinding in sequence, and timely removing most impurity dust by pumping to obtain the more than 200 meshes of reduced material.

Fourthly, grinding the raymond: and (3) circularly grinding, ash pumping and dust removing the 200-mesh reduced material by a Raymond mill, a coarse-fine separation device and a centrifugal pumping device in sequence to obtain a 300-mesh reduced material.

Optimizing magnetic separation: the separation material with the granularity of more than 200 meshes is sequentially selected by a medium magnetic separator, a strong magnetic selection device and a medium magnetic selection device, reduced iron powder is optimally extracted, nonmagnetic heavy metal is separated, and an optimized product is finally obtained: optimized nickel alloy Ni8.23%, optimized reduced iron fine powder Fe80.13%, phosphorus-containing P0.015% and sulfur-containing 0.018%;

energy consumption per ton ore: the standard coal consumption for roasting and heating is 77.47 kg/ton ore, and the electricity consumption for magnetic separation is optimized to be 67 degrees/ton ore.

Example 2

0.86 percent of certain low-grade laterite-nickel ore Ni0.23 percent and Fe50.23 percent. The method comprises the following steps:

firstly, raw material treatment: screening, granulating, drying and screening raw materials of 0.86% of Ni0.86% and Fe50.23% of laterite-nickel ore to obtain nickel ore particles with the particle size of 3-40mm, wherein the weight percentage of water is less than 10%;

Optimizing magnetic separation: the separation material with the granularity of more than 200 meshes is sequentially selected by a medium magnetic separator, a strong magnetic selection device and a medium magnetic selection device, reduced iron powder is optimally extracted, nonmagnetic heavy metal is separated, and an optimized product is finally obtained: optimized Ni alloy Ni8.25 wt%, optimized Fe refined powder Fe81.62 wt%, P0.014 wt% and S0.016 wt%.

Energy consumption per ton ore: the standard coal consumption for roasting and heating is 79.16 kg/ton ore, and the electricity consumption for magnetic separation is optimized to be 65 degrees/ton ore.

While the invention has been described in further detail with reference to specific preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. The utility model provides a device of low-grade laterite-nickel ore deposit is optimized in gas base direct reduction magnetic separation, a serial communication port, including the kiln body (1), be provided with circuitous snakelike flue from top to bottom in the kiln body (1), snakelike flue from the top down divide into the three-layer, does in proper order: a roasting preheating section (5), a roasting heating section (6) and a roasting reduction section (7); the roasting preheating section (5) is connected with a flue gas collecting and air inducing device (701), a preheating material pool (2) is arranged above the roasting preheating section (5), the preheating material pool (2) is communicated with the roasting preheating section (5) through a preheating material pipe (3), the bottom of the roasting preheating section (5) is communicated with a vertical blanking channel (4), and the blanking channel (4) penetrates through the roasting heating section (6) and the roasting reduction section (7) and is isolated from the roasting heating section (6) and the roasting reduction section (7); the roasting reduction section (7) is connected with a burner of a combustion chamber (25); the roasting heating temperature in the roasting reduction section (7) is 960-1030 ℃; the bottom end of the blanking channel (4) is communicated with an air cooling pipe (10) for cooling materials, and a reducing gas preheating and reducing device (9) is arranged in the air cooling pipe (10); the reducing gas preheating and reducing device (9) is communicated with a reducing gas pipeline; the pressure of the reducing gas is 600-1200 Pa; the bottom of the air cooling pipe (10) is connected with a material output device (14), and the material output device (14) is sequentially connected with a pair-roller circulating grinding system, a Raymond circulating grinding system and a magnetic separation optimization system.

2. The device for optimizing the low-grade laterite-nickel ore by gas-based direct reduction magnetic separation according to claim 1, characterized in that a reducing gas outlet of the reducing gas preheating reduction device (9) is arranged at the upper end in the air-cooled pipe (10) and faces the blanking channel (4); the heat preservation structure is wrapped above the middle part of the air cooling pipe (10).

3. The device for optimizing the low-grade laterite-nickel ore by gas-based direct reduction and magnetic separation according to claim 1 is characterized in that an air inlet preheater (16) is arranged outside the air-cooled pipe (10), the outlet of the cooling hot air collector (17) is connected with the inlet of the air inlet preheater (16), and the air inlet preheater (16) is connected with the burner of the combustion chamber (25).

4. The device for optimizing the low-grade laterite-nickel ore by gas-based direct reduction magnetic separation according to claim 1, characterized in that the temperature of the material is cooled to 45-55 ℃ after passing through the air-cooled pipe (10).

5. The device for optimizing low-grade lateritic nickel ore by gas-based direct reduction magnetic separation according to claim 1, further comprising a raw material handling system, wherein the raw material handling system comprises a nickel ore screening granulator (101), a flue gas cleaning dryer (102) and a nickel ore screening output device (103) which are connected in sequence, and the nickel ore screening output device (103) is connected with the preheating feed tank (2); the smoke collection and air induction device (701) is connected with the smoke purification dryer (102).

6. The device for optimizing low-grade laterite-nickel ore by gas-based direct reduction magnetic separation according to claim 1, characterized in that the paired-roller circulating grinding system comprises a paired-roller mill (301), a screening and extracting device (302) and a hoisting machine (303) which are connected in sequence; the Raymond circular grinding system comprises a Raymond mill (401), a coarse-fine separation device (402) and a centrifugal pumping device (403) which are sequentially connected; the magnetic separation system comprises a middle magnetic separator (501), a strong magnetic separation device (502) and a middle magnetic separation device (503) which are sequentially connected.

7. The device for optimizing the low-grade lateritic nickel ore by gas-based direct reduction magnetic separation according to claim 6, further comprising an ash removing and dust removing device (601) and an electrostatic dust removing device (602) which are connected, wherein the screening and extracting device (302) and the medium magnetic separator (501) are respectively connected with the ash removing and dust removing device (601).

8. Method for optimizing low-grade lateritic nickel ore by gas-based direct reduction magnetic separation according to any one of the claims 1 to 7, characterized by comprising the following steps:

a) raw material treatment: screening, granulating, drying and screening low-grade laterite-nickel ore to obtain laterite-nickel ore particle material with the particle size of 3-40mm, wherein the water content is less than 10% by weight;

b) gas-based direct reduction roasting: when the smoke temperature of the roasting reduction section (7) reaches 900-; meanwhile, reducing gas is introduced into the blanking channel (4), and when the flue gas temperature of the roasting reduction section (7) reaches 980 ℃, the blanking speed is v 2; v2 is 5-6 times of v 1; tiling and stacking the low-grade laterite-nickel ore particle material in a preheating material pool to achieve a thickness of 200-300 mm; the rising speed of the flue gas temperature in the roasting reduction section (7) is less than or equal to 2 ℃/min;

c) the laterite nickel ore particle material after gas-based direct reduction roasting enters an air cooling pipe (10);

9. The method for optimizing low-grade lateritic nickel ore by gas-based direct reduction magnetic separation according to claim 8, characterized in that the lateritic nickel ore particulate material is discharged by controlling the rotating speed of a guide impeller, the rotating speed of the guide impeller is 4-6 r/h.