阅读说明：本技术 两段还原挥发富集低品位锗精矿中锗的设备及方法 (Device and method for enriching germanium in low-grade germanium concentrate through two-stage reduction and volatilization ) 是由 熊浩 普世坤 张红潇 柴皓茗 邵雨萌 尹国文 罗中旭 于 2021-08-02 设计创作，主要内容包括：本发明涉及锗回收提取技术领域,具体公开一种经两段还原挥发富集低品位锗精矿中锗的设备及方法,包括顺序连接的氮气供气设备、旋转式挥发炉、竖式还原炉和布袋收尘器,所述竖式还原炉还连接有氢气供气装置和盐酸处理池,将低品位锗精矿粉碎后加入还原剂,混合均匀,然后放入旋转式挥发炉中,将旋转式挥发炉,先进行氧化焙烧挥发以除去低温下易挥发物质,然后将旋转式挥发炉升温,进行锗的第一段还原挥发,挥发后的锗进入竖式还原炉,通入氢气还原后,得到含锗固体颗粒,在加入盐酸进行反应后分离得到锗金属,采用两段富集锗工艺,提高了锗精矿二次富集的富集倍数和锗精矿的品位,解决了后工序氯化提锗回收率下降、成本高、环境影响大等问题。(The invention relates to the technical field of germanium recovery and extraction, and particularly discloses equipment and a method for enriching germanium in low-grade germanium concentrate through two-stage reduction and volatilization, which comprises nitrogen gas supply equipment, a rotary volatilization furnace, a vertical reduction furnace and a bag dust collector which are sequentially connected, wherein the vertical reduction furnace is also connected with a hydrogen gas supply device and a hydrochloric acid treatment pool, the low-grade germanium concentrate is crushed and then added with a reducing agent to be uniformly mixed, then the rotary volatilization furnace is put into the rotary volatilization furnace, the rotary volatilization furnace is firstly oxidized, roasted and volatilized to remove volatile substances at low temperature, then the rotary volatilization furnace is heated to carry out first-stage reduction volatilization of germanium, the volatilized germanium enters the vertical reduction furnace, hydrogen is introduced for reduction to obtain germanium-containing solid particles, hydrochloric acid is added for reaction and then germanium metal is separated to obtain germanium metal, and a two-stage germanium enriching process is adopted, so that the enrichment multiple of secondary enrichment of the germanium concentrate and the grade of the germanium concentrate are improved, solves the problems of low recovery rate, high cost, large environmental impact and the like of the chlorination germanium extraction in the subsequent process.)

1. The equipment is characterized by comprising a nitrogen gas supply device, a rotary volatilization furnace, a vertical reduction furnace and a bag dust collector which are sequentially connected, wherein the vertical reduction furnace is also connected with a hydrogen gas supply device and a hydrochloric acid treatment pool, the rotary volatilization furnace comprises a closed rotary air inlet, a first shell, a first furnace body, first heat insulation cotton, a first heating resistance wire and a motor, the first shell is sleeved outside the first furnace body and the motor, the first heat insulation cotton is filled between the first shell and the first furnace body, the first heating resistance wire is arranged on the outer wall of the first furnace body, the motor is arranged below the first furnace body and separated from the first furnace body by a first heat insulation plate, the first furnace body is driven to rotate by a gear set meshed with three gears, a boat-shaped material tray is arranged inside the first furnace body, and a feed inlet is arranged on the shell corresponding to the boat shape, the rotary air inlet is arranged on the first shell and connected with nitrogen supply equipment, and an air outlet is arranged at the corresponding position and connected with the vertical reduction furnace through a pipeline.

2. The apparatus of claim 1, wherein the vertical reduction furnace comprises a second shell, a second furnace body, the second shell is sleeved outside the second furnace body, a second heat insulation plate is arranged in the middle between the second shell and the second furnace body for separating, so that the upper half section forms a low temperature region, the lower half section forms a high temperature region, a cooling pipe is arranged in the low temperature region, second heat insulation cotton and a second heating resistance wire are arranged in the high temperature region, a round material tray is arranged at the bottom of the second furnace body, a conical air outlet is arranged at the top of the second furnace body, filter cloth is arranged in front of the conical air outlet, a cavity is arranged at the bottom of the high temperature region, the cavity is formed by the outer shell of the annular chamber, hydrogen is arranged at the bottom of the cavity, an air inlet gap is formed by an opening between the second furnace body and the air inlet of the cavity, and flue gas is arranged at the upper part of the air inlet gap, the flue gas inlet hole is connected with the rotary volatilization furnace through a pipeline.

3. The apparatus for two-stage reductive volatilization enrichment of germanium in germanium concentrate according to claim 1, wherein the hydrogen supply device comprises a hydrogen source and a hydrogen buffer tank, the bag dust collector is further connected with a hydrogen recovery device, and the hydrogen recovery device inputs the recovered hydrogen into the hydrogen buffer tank.

4. A method for enriching germanium in germanium concentrate by two-stage reduction and volatilization is characterized by comprising the following steps:

(1) crushing the germanium concentrate to below 200 meshes, adding a reducing agent in a certain proportion, uniformly mixing, and then putting the mixed material into a rotary volatilization furnace through a feed inlet;

(2) opening a nitrogen gas supply device, introducing into the equipment of any one of claims 1-3 through a rotary air inlet, and continuously introducing for more than 30 min;

(3) preheating a rotary volatilizing furnace to 650 ℃, and firstly carrying out oxidizing roasting volatilization to remove volatile substances at low temperature;

(4) heating the rotary volatilizing furnace to 1000-1100 ℃, and turning on a motor to drive the furnace body to rotate, so that the germanium concentrate is fully contacted with a reducing agent to carry out reduction volatilization of germanium;

(5) the smoke dust containing germanium monoxide after reduction and volatilization enters a vertical reduction furnace from a smoke gas inlet, hydrogen is introduced at the same time, the hydrogen uniformly enters a furnace body through an annular cavity outer shell and an air inlet gap at the bottom, the temperature of the lower half section of the vertical reduction furnace is raised to 800 ℃, meanwhile, a cooling pipe at the upper half section is continuously filled with condensate, the smoke dust containing germanium monoxide and the circularly introduced hydrogen fully react in a high-temperature zone of the furnace body, and the generated germanium metal is collected in a circular material tray at the bottom of the furnace body;

(6) and putting the solid collected by the circular material tray after the reaction in the shaft furnace body into a hydrochloric acid treatment tank, and screening to obtain the germanium metal.

5. The method for two-stage reduction and volatilization enrichment of germanium in low-grade germanium concentrate according to claim 4, wherein the reducing agent is sodium borohydride.

6. The method for enriching the germanium in the low-grade germanium concentrate by two-stage reduction volatilization according to claim 5, wherein the germanium ore is the low-grade germanium concentrate, and the germanium content is lower than 2%.

7. The method for enriching germanium in low-grade germanium concentrate through two-stage reduction volatilization according to claim 6, wherein the mass ratio of the low-grade germanium concentrate to sodium borohydride is 20:1, and the mixed material is placed into a boat-shaped tray of a rotary volatilization furnace to have a thickness of 30 mm.

8. The method for enriching the germanium in the low-grade germanium concentrate by two-stage reductive volatilization according to claim 4, wherein the reductive volatilization time of the germanium in the step (4) is 1 h.

9. The method for enriching germanium in low-grade germanium ore by two-stage reduction volatilization according to claim 2, wherein the filter cloth is a high-temperature resistant polyester fiber non-woven fabric.

Technical Field

The invention relates to the technical field of germanium recovery and extraction, in particular to equipment and a method for enriching germanium in low-grade germanium concentrate through two-stage reduction and volatilization.

Background

The metal germanium has good semiconductor properties, is an important basic raw material in the fields of information communication and new energy, and is widely applied to military and civil fields such as optical fiber communication, polyester PET catalysts, high-frequency and ultrahigh-frequency electronic devices, infrared optics, solar photovoltaic cells, aerospace measurement and control, nuclear physical detection, biomedicine and the like.

Germanium is mainly associated with germanium-containing lignite and zinc blende. China has rich reserves of germanium-containing coal, but the content is extremely low, the distribution is wide, and the efficient extraction of germanium is difficult. In China, the germanium-containing lignite is mainly used for vortex smelting power generation, most of germanium is enriched in the fly ash in the combustion process, but the germanium content is low, the components are complex, and particularly the silicon content has a serious influence on the enriched germanium. At present, common methods for enriching germanium from waste residues comprise a pyrogenic volatilization enrichment method and a wet separation enrichment method.

The function of rare-dispersion metal germanium in national economy is increasingly important, but in recent years, the grade of coal-mining germanium ore is lower and lower, the grade of produced germanium concentrate is gradually reduced, the comprehensive yield of wet chlorination germanium extraction is relatively reduced, and the conventional wet germanium extraction process of fly ash comprises chlorination leaching, distillation, hydrolysis, reduction and zone melting to prepare high-purity germanium. However, the content of germanium in the fly ash is very low, only about 0.5 percent, and the direct wet method for extracting germanium has the disadvantages of large reagent consumption and high cost; the environmental protection pressure is large, the amount of generated waste residue and waste water is large, the arsenic content is high, and the treatment is difficult.

The method for enriching germanium by pyrogenic process is characterized by utilizing the volatility of germanium, volatilizing the germanium into smoke dust under the high-temperature state so as to obtain indium enriched substance in the smoke dust, namely germanium smoke dust. The problem of low germanium coal dust treatment is that slag fusion and bonding phenomena are easily generated in the process of high-temperature roasting and volatilizing germanium, so that the phenomenon of air permeability is reduced, the phenomenon of burning is generated, even the equipment operation is influenced, and germanium cannot be volatilized due to slag wrapping, so that the germanium volatilization rate is extremely low.

The vortex smelting power generation of the germanium-containing lignite and the classical wet germanium extraction are mature technologies, and the two technologies are upgraded and modified, so that the problems of high cost, high technical difficulty and the like exist. A fly ash secondary germanium enrichment module is embedded between the germanium coal power generation module and the wet germanium extraction module, so that reagent consumption and three-waste reduction can be reduced.

Disclosure of Invention

The invention aims to solve the problems existing in the treatment of the low-grade germanium concentrate, and provides a method for volatilizing and enriching germanium in the low-grade germanium concentrate by two-section reduction by using sodium borohydride and hydrogen as reducing agents, and a method and equipment for extracting germanium in the low-grade germanium concentrate.

In order to achieve the above purpose, the invention provides the following technical scheme:

a device for two-section reduction volatilization enrichment of germanium in low-grade germanium concentrate comprises a nitrogen gas supply device, a rotary volatilization furnace, a vertical reduction furnace and a bag dust collector which are sequentially connected, wherein the vertical reduction furnace is also connected with a hydrogen gas supply device and a hydrochloric acid treatment pool, the rotary volatilization furnace comprises a closed rotary air inlet, a first shell, a first furnace body, first heat insulation cotton, a first heating resistance wire and a motor, the first shell is sleeved outside the first furnace body and the motor, the first heat insulation cotton is filled between the first shell and the first furnace body, the first heating resistance wire is arranged on the outer wall of the first furnace body, the motor is arranged below the first furnace body and separated from the first furnace body by a first heat insulation plate, the first furnace body is driven to rotate by three gear sets engaged with each other, a boat-shaped material tray is arranged inside the first furnace body, and a feed inlet is arranged on the shell corresponding to the boat-shaped material tray, the rotary air inlet is arranged on the first shell and connected with nitrogen supply equipment, and an air outlet is arranged at the corresponding position and connected with the vertical reduction furnace through a pipeline.

Respectively grinding low-grade germanium concentrate and sodium borohydride, then placing the ground low-grade germanium concentrate and the sodium borohydride on a boat-shaped tray, uniformly mixing the ground low-grade germanium concentrate and the sodium borohydride, enabling the ground low-grade germanium concentrate and the sodium borohydride to enter a rotary volatilization furnace through a feed inlet, starting a motor to drive a furnace body to rotate, preheating the furnace body to 650 ℃, performing oxidizing roasting volatilization to remove volatile unburned coal tar, water and other substances at low temperature, heating the rotary volatilization furnace to 1000-1100 ℃, enabling the low-grade germanium concentrate and the sodium borohydride in the furnace body to be in full contact, and improving the reaction efficiency.

The rotary volatilization furnace is also provided with a sealed rotatable air inlet hole, inert gas nitrogen is filled into the furnace body through the air inlet hole, smooth air inlet can be ensured simultaneously when the rotary volatilization furnace works, the air inlet pipe cannot rotate along with the volatilization furnace, and the sealing performance is good.

The vertical reduction furnace comprises a second shell and a second furnace body, wherein the second shell is sleeved outside the second furnace body, a second heat insulation plate is arranged in the middle between the second shell and the second furnace body to separate the second shell from the second furnace body, the upper half section of the second shell forms a low-temperature area, the lower half section of the second shell forms a high-temperature area, a cooling pipe is arranged in the low-temperature area, second heat insulation cotton and a second heating resistance wire are arranged in the high-temperature area, a circular material disc is arranged at the bottom of the second furnace body, a conical air outlet hole is formed in the top of the second furnace body, high-temperature resistant filter cloth is arranged in front of the conical air outlet hole, a cavity is arranged at the bottom of the high-temperature area, the cavity is formed by the outer shell of the annular cavity, a hydrogen gas inlet hole is formed in the bottom of the cavity, an opening is formed between the second furnace body and the cavity, and a flue gas inlet hole is formed in the upper portion of the air inlet hole.

The hydrogen of the vertical reduction furnace enters an annular chamber from a hydrogen inlet hole, is connected with the furnace body through a small gap, is compressed through a triangular chamber and then enters the furnace body from the gap, is preheated in advance, and uniformly distributed to enter the furnace body to perform reduction reaction with gaseous germanium monoxide and other impurities which may volatilize to enter the furnace body,

the heating resistance wire of the vertical reduction furnace is arranged at the lower half section of the furnace body, the cooling pipe is arranged at the upper half section of the furnace body, the vertical reduction furnace is divided into two temperature areas, filter cloth is arranged in front of an air outlet hole above the vertical reduction furnace, smoke volatilized into the furnace body moves upwards and enters a low-temperature area to be cooled into solid or liquid, the smoke enters a high-temperature area below the vertical reduction furnace and falls into a high-temperature area below the vertical reduction furnace again due to the blocking of the filter cloth, hydrogen and other waste gas can enter a cloth bag dust collector from the low-temperature area above the vertical reduction furnace, and metal elements reduced by the hydrogen are collected in a material tray at the bottom of the furnace body.

The invention also provides a method for enriching germanium in low-grade germanium concentrate by two-time reduction and volatilization, which specifically comprises the following steps:

1) crushing the germanium concentrate to below 200 meshes, adding a reducing agent in a certain proportion, uniformly mixing, and then putting the mixed material into a rotary volatilization furnace through a feed inlet;

2) connecting the whole equipment, filling nitrogen into the equipment through a rotary air inlet, and continuously introducing the nitrogen for 30 minutes to ensure that the whole equipment is completely filled with the nitrogen;

3) preheating a rotary volatilization furnace to 650 ℃, and firstly carrying out oxidizing roasting volatilization to remove volatile unburned coal tar, water and other substances at low temperature;

4) heating the rotary volatilization furnace to about 1000-1100 ℃, turning on a motor to drive the furnace body to rotate, fully contacting low-grade germanium concentrate with sodium borohydride, and carrying out reduction volatilization of germanium, wherein the related reaction equation is as follows:

NaBH₄+4GeO₂＝4GeO(g)+NaBO₂+2H₂O(g)；

5) the smoke dust containing germanium monoxide enters a vertical reduction furnace from a smoke gas inlet after reduction and volatilization, hydrogen for preheating and heat preservation is introduced at the same time, the hydrogen passes through an annular cavity outer shell and an air inlet gap at the bottom, the temperature of two sections of the vertical reduction furnace is between 800 ℃ and 100 ℃ from bottom to top, the smoke dust containing germanium monoxide and the hydrogen introduced circularly react fully in a high-temperature zone of a furnace body, and the generated germanium metal is collected in a circular material disc at the bottom of the furnace body, and the related reaction equation is as follows:

GeO(g)+H₂(g)＝Ge+H₂0(g)

other impurities that may be reduced by hydrogen react as:

MgO+H₂(g)＝Mg+H₂O(g)

Al₂O₃+3H₂(g)＝2Al+3H₂O(g)

Fe₂O₃+3H₂(g)＝2Fe+3H₂O(g)

CaO+H₂(g)＝Ca+H₂O(g)

6) putting the solid collected by the round material tray after the reaction in the vertical reduction furnace into a hydrochloric acid reaction tank, and screening to obtain germanium metal, wherein the involved reaction equation is as follows:

Mg+2HCl＝MgCl₂+H₂(g)

MgO+2HCl＝MgCl₂+H₂O

7) waste gas generated by the vertical reduction furnace and hydrochloric acid treatment enters hydrogen recovery equipment, reaches the industrial production use standard after dust removal, oil removal, oxygen removal and water removal, enters a hydrogen buffer tank, is repeatedly recycled, and reduces the cost;

8) after two times of reduction, volatilization and enrichment, germanium concentrate containing germanium metal with the germanium content of more than 40 percent is obtained. Compared with the prior art, the invention has the following beneficial effects:

(1) the rotary tube furnace with novel design is adopted, and the low-grade germanium concentrate is fully contacted with the reducing agent through the rotary design of the furnace body, so that the reaction efficiency is improved;

(2) the process of enriching germanium twice by adopting nitrogen, sodium borohydride, a rotary volatilizing furnace, hydrogen and a vertical reduction furnace improves the enrichment multiple of germanium ore smelting and the grade of germanium concentrate, and solves the problems that the recovery rate of germanium extraction by chlorination in the subsequent process is reduced, the production cost is greatly increased, and the harmless treatment pressure of the generated three wastes, residual acid, residues and waste gas is large;

(3) the introduction of inert gas nitrogen as the carrier gas of volatile components effectively solves the problems that germanium smoke dust is easy to adhere to the pipe wall and block in a cooling pipeline in the traditional dust collecting system, and simultaneously forms inert atmosphere to isolate air and prevent generated germanium smoke dust from being oxidized into GeO₂；

(4) The introduction of the reducing agent sodium borohydride overcomes the defect that germanium in the lignite cannot be reduced to the maximum extent to be volatilized by taking C in the germanium concentrate as the reducing agent in the lignite germanium concentrate;

(5) introducing reducing agent hydrogen, heating to 800 ℃ to sublimate GeO, and reacting with the hydrogen, so that the grade of the germanium concentrate is further improved, the reaction efficiency is improved, and the cost of the subsequent process is reduced;

(6) the temperature gradient design of the vertical reduction furnace can prevent the flue gas containing germanium monoxide from escaping from a gas outlet for hydrogen circulation, so as to achieve the purpose of hydrogen circulation in the furnace body;

(7) the design of the hydrogen gas inlet holes distributed at the bottom of the vertical reduction furnace can ensure that hydrogen enters the furnace body from all directions to react with the flue gas in the furnace body and circulates from bottom to top, so that the gas in the furnace body flows, the contact between the hydrogen and the flue gas is increased, the reaction is accelerated, and the reaction efficiency and the utilization rate of the hydrogen are improved;

(8) the introduction of the hydrogen recovery device can save the cost and improve the utilization rate of hydrogen;

(9) the introduction of hydrochloric acid treatment, reaction dissolution and removal of other metal impurities which can be reduced and other metal oxide impurities which are not reduced in the reduction furnace, and further improvement of the grade of the germanium concentrate through simple steps;

(11) the obtained germanium concentrate has high grade which is more than 40 percent, and is beneficial to the further wet extraction of germanium in the subsequent process.

Drawings

FIG. 1 is a schematic diagram of the apparatus and process of the present invention;

FIG. 2 is a schematic view of a rotary volatilization furnace of the present invention;

FIG. 3 is a schematic view of a vertical reduction furnace according to the present invention;

the furnace comprises a first shell 1, a first furnace body 2, first heat insulation cotton 3, a first heating resistance wire 4, a motor 5, a gear set 6, a rotary air inlet 7, a feed inlet 8, a first heat insulation plate 9 and a boat-shaped tray 10, wherein the first shell is a hollow shell; the furnace comprises a second shell 11, a second furnace body 12, second heat insulation cotton 13, second heating resistance wires 14, a cooling pipe 15, a second heat insulation plate 16, a hydrogen gas inlet hole 17, a cavity shell 18, a cavity 19, an air inlet gap 20, a flue gas inlet hole 21, a conical air outlet hole 22, a circular material tray 23, filter cloth 24, a high-temperature area 25 and a low-temperature area 26.

Detailed Description

The invention is further described with reference to the following figures and specific examples.

Example 1

As shown in fig. 1, an apparatus for twice reduction, volatilization and enrichment of germanium in low-grade germanium concentrate comprises a nitrogen gas supply device, a rotary volatilization furnace, a vertical reduction furnace and a bag collector which are connected in sequence, wherein the vertical reduction furnace is further connected with a hydrogen gas supply device and a hydrochloric acid treatment pool, the nitrogen gas supply device is a nitrogen gas bottle, the hydrogen gas supply device comprises a hydrogen source and a hydrogen buffer tank, the bag collector is further connected with a hydrogen recovery device, and the hydrogen recovery device inputs the recovered hydrogen into the hydrogen buffer tank for recycling.

As shown in fig. 2, the rotary volatilization furnace comprises a closed rotary air inlet 7, a first shell 1, a first furnace body 2, first heat insulation cotton 3, a first heating resistance wire 4 and a motor 5, wherein the first shell 1 is sleeved outside the first furnace body 2 and the motor 5, the first heat insulation cotton 3 is filled between the first shell 1 and the first furnace body 2, the first heating resistance wire 4 is arranged on the outer wall of the first furnace body 2, the motor 5 is arranged below the first furnace body 2 and is separated from the first furnace body 2 by a first heat insulation plate 9, the first furnace body 2 is driven to rotate by a gear set 6 meshed with three gears, a boat-shaped material disc 10 is arranged inside the first furnace body 2, and a feed inlet 8 is arranged on a shell corresponding to the boat-shaped material disc 10.

The rotary volatilization furnace is provided with a sealed rotatable air inlet 7, inert gas nitrogen is filled into the furnace body through the rotary air inlet 7, smooth air inlet can be ensured simultaneously when the rotary volatilization furnace works, the air inlet pipe cannot rotate along with the volatilization furnace, the airtightness is good, an air outlet is arranged on the other side of the first furnace body and is symmetrical to a rotary proceeding hole, and the air outlet is connected to a flue gas inlet hole of the vertical reduction furnace through a pipeline.

As shown in fig. 3, the vertical reduction furnace includes a second shell 11, a second furnace body 12, the second shell 11 is sleeved outside the second furnace body 12, and a second thermal baffle 16 is arranged in the middle between the second shell 11 and the second furnace body 12 for separating, so that the upper half section forms a low temperature region 26, the lower half section forms a high temperature region 25, a cooling pipe 15 is arranged in the low temperature region 26, second thermal insulation cotton 13 and a second heating resistance wire 14 are arranged in the high temperature region 25, a circular material tray 23 is arranged at the bottom of the second furnace body 12, a conical air outlet 22 is arranged at the top, a high temperature resistant filter cloth 24 is arranged in front of the conical air outlet 22, a cavity 19 is arranged at the bottom of the high temperature region 25, the cavity is formed by an annular chamber outer shell 18, a hydrogen 17 is arranged at the bottom of the cavity 19, an opening is arranged between the second furnace body 12 and the cavity 19 to form an air inlet gap 20, and a flue gas inlet 21 is arranged at the upper part of the air inlet gap 20.

The hydrogen of the vertical reduction furnace enters an annular cavity from a hydrogen inlet hole, the cavity is connected with a furnace body through a fine gap, the hydrogen is compressed by the cavity and then enters the furnace body from an air inlet gap, the hydrogen can be preheated in advance, and uniformly distributed in the furnace body to carry out reduction reaction with gaseous germanium monoxide and other impurities which may volatilize and enter the furnace body, a heating resistance wire of the vertical reduction furnace is arranged at the lower half section of the furnace body, the heating resistance wire is externally connected with a heating motor device to control heating temperature, a cooling pipe is arranged at the upper half section of the furnace body, the cooling pipe is a high-temperature glass pipe and is externally connected with a condensing device to control the circulating input of condensate to achieve the purpose of rapid cooling, so that the vertical reduction furnace is divided into two temperature zones, filter cloth is arranged in front of an air outlet hole above the vertical reduction furnace, the material of the filter cloth is high-temperature resistant polyester fiber non-woven fabric, the mesh hole is smaller than 200 meshes, and the smoke which volatilizes and enters the furnace body to move upwards to enter a low temperature zone to be cooled into solid or liquid, and due to the blocking of the filter cloth, the hydrogen and other waste gases can fall into the high-temperature area below again, the hydrogen and other waste gases can enter the cloth bag dust collector from the low-temperature area above, and the metal elements reduced by the hydrogen are collected in a material tray at the bottom of the furnace body.

The method for enriching germanium in low-grade germanium concentrate by two-stage reduction and volatilization comprises the following steps:

1) crushing 5kg of low-grade germanium concentrate with 0.99 percent of germanium content to 200 meshes, adding 0.25kg of sodium borohydride, uniformly mixing on a boat-shaped tray 10, wherein the thickness of a material layer is 30mm, and then putting the mixed material into a rotary volatilization furnace through a feed inlet 8;

2) connecting subsequent equipment, starting the motor 5 to drive the first furnace body to rotate, filling nitrogen into the equipment through an air inlet, and continuously introducing the nitrogen, wherein the flow rate of a carrier gas is 0.5L/min, so that all the furnace bodies of the equipment are completely filled with the nitrogen;

3) preheating a rotary volatilization furnace to 650 ℃, and firstly carrying out oxidizing roasting for 1h to volatilize so as to remove volatile unburned coal tar, water and other substances at low temperature;

3) heating the rotary volatilization furnace to 1100 ℃, increasing the flow of the carrier gas to 1L/min, fully contacting the low-grade germanium concentrate with sodium borohydride, carrying out reduction volatilization for 1h,

4) the smoke dust containing germanium monoxide after reduction and volatilization enters a vertical reduction furnace from a smoke gas inlet hole, hydrogen is introduced into the vertical reduction furnace in advance at the flow rate of 1L/min for 20 minutes, the hydrogen flow rate is slowly regulated to 0.1L/min after the vertical reduction furnace is filled, the hydrogen uniformly enters a second furnace body 12 from an air inlet gap 20 through a cavity 19 at the bottom, the temperature of two sections of the vertical reduction furnace is 800-100 ℃, the smoke dust containing germanium monoxide and the hydrogen circularly introduced are fully reacted in a high-temperature zone 25 of the furnace body, and the generated germanium concentrate metal is collected in a circular material tray 23 at the bottom of the furnace body,

5) and reacting the solids collected by the circular material disc 23 after reaction in the second furnace body with sufficient hydrochloric acid until no bubbles appear, and filtering and separating to obtain the germanium concentrate metal.

6) Waste gas generated by the vertical reduction furnace and hydrochloric acid treatment enters hydrogen recovery equipment, reaches the industrial production use standard after dust removal, oil removal, oxygen removal and water removal, enters a hydrogen buffer tank, is repeatedly recycled, and reduces the cost;

8) after two times of reduction, volatilization and enrichment, high-grade germanium concentrate with over 40 percent of germanium is obtained, and the recovery of the germanium reaches 99 percent.