Method and apparatus for secondary enrichment and recovery of germanium from low-grade lignite germanium concentrates with by microwave heating in vacuum

Abstract

Provided is a method and apparatus for secondary enrichment of germanium from low-grade lignite germanium concentrates in vacuum, and particularly a method and apparatus for secondary enrichment and recovery of germanium from low-grade lignite germanium concentrates with microwave heating in vacuum, which belongs to a germanium extraction method and apparatus in the field of metallurgy.

Claims

1. A method for secondary enrichment and recovery of germanium from a low-grade lignite germanium concentrate with microwave heating in vacuum, comprising: transferring a low-grade lignite germanium concentrate into a material crucible and placing the material crucible containing the low-grade lignite germanium concentrate in a heating chamber of a microwave heating device for vacuum volatilization; and closing the heating chamber and connecting pipes of each part of the heating chamber; starting a vacuum device to reduce pressure in the heating chamber to be lower than 1,000 Pa; starting the microwave heating device to increase temperature to 900-1,100 C. at a rate of 20-50 C. per minute; opening a valve of an inert gas to supply the inert gas at an influx of 1-3 liters per minute; after reacting for 1-3 hours at a constant temperature, when germanium and other volatile substances volatize into smoke and into a dust collecting system, stopping heating; supplying the inert gas to the heating chamber to cool the heating chamber to room temperature; and after stopping vacuum, starting a settling and collecting chamber and a bag dust collecting chamber for collecting dust; combining the dust to obtain a germanium concentrate.

2. The method according to claim 1, further comprising: adding to the germanium concentrate 10 mol/L hydrochloric acid at an amount of 4-5 times the weight of the germanium concentrate and water at an amount of the same weight of the germanium concentrate to obtain a mixture; mixing the mixture uniformly; and performing distillation and separation of the mixture to obtain GeCl.sub.4.

3. An apparatus for secondary enrichment and recovery of germanium from a low-grade lignite germanium concentrate with microwave heating in vacuum, comprising: a microwave heating system; a settling and collecting system; a bag dust collecting system; an exhaust absorbing system; a vacuum system; an inert gas protecting system; and a water cooling system, wherein the microwave heating system, the settling and collecting system, and the bag dust collecting system are sequentially connected via pipes; an exhaust from the bag dust collecting system is processed by the exhaust absorbing system; the inert gas protecting system is in fluid connection with the microwave heating system; vacuum pumping of the apparatus is performed by the vacuum system; and cooling is performed by the water cooling system.

4. The apparatus according to claim 3, wherein the microwave heating system comprises: a microwave generator; a heating chamber; a material crucible; and a material supplying and discharging device, wherein the low-grade lignite germanium concentrate is placed in the material crucible in the heating chamber; the microwave generator encloses the heating chamber; the inert gas protecting system is in fluid connection with the heating chamber; a water-cooled vacuum-sealed flange of the water cooling system is provided between the heating chamber and the microwave generator; the heating chamber is in fluid connection with the settling and collecting system via a pipe on which another water-cooled vacuum-sealed flange of the water cooling system is provided; the settling and collecting system has a settling and collecting chamber that is configured to settle large particles in a gas stream entering a settling and collecting container; fine particles having a high germanium content carried by the gas stream enter the bag dust collecting system; the bag dust collecting system filters the fine particles having a high germanium content carried by the gas stream to collect a germanium enriched product that is rough germanium oxide and discharges an exhaust; the exhaust enters the exhaust absorbing system, the exhaust is absorbed by a weak alkali solution in the exhaust absorbing system and then discharged; a water-cooled vacuum-sealed flange is provided to cool the gas stream entering the settling and collecting container; and the vacuum system is provided at an end of the apparatus; and the vacuum system has a vacuum valve and a mechanical pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flowchart showing a process for extracting germanium including MnO.sub.2HCl heating, leaching, distilling and separating;

(2) FIG. 2 is a flowchart showing a process for extracting germanium according to an embodiment;

(3) FIG. 3 is a schematic connection view of the apparatus according to an embodiment; and

(4) FIG. 4 is a schematic structural view of the apparatus according to an embodiment;

(5) wherein: 1 refers to a microwave heating system; 2 a setting and collecting system; 3 a bag-type dust collecting system; 4 an exhaust absorbing system; 5 a vacuum system; 6 an inert gas protecting system; 7 a water cooling system; 1-1 a microwave generator; 1-2 microwave generator; 1-3 a material crucible; 1-4 a material supplying and discharging device; 2-1 a setting and collecting container; 5-1 a vacuum valve; 5-2 a mechanical pump; and 7-1 a water-cooled vacuum-sealed flange.

DETAILED DESCRIPTION

(6) The embodiments disclosed herein relate to a method for secondary enrichment and recovery of germanium from low-grade lignite germanium concentrates by microwave heating in vacuum.

Embodiment 1

(7) A method for secondary enrichment and recovery of germanium from low-grade lignite germanium concentrates by microwave heating in vacuum includes the following steps. The germanium concentrate shown in Table 1 is used as the raw material.

(8) TABLE-US-00001 TABLE 1 Main Chemical Composition of Germanium Concentrates Composition Loss on Ge SiO.sub.2 Fe.sub.2O.sub.3 Al.sub.2O.sub.3 As CaO MgO S Ignition Content % 0.5-3.0 60-70 4-10 10-15 0.1-0.3 2-5 1-2 1-2.0 12.10

(9) Step 1: Weigh 1,000 g of germanium concentrates with a germanium content of 1.01%, and put the same into a high alumina crucible having a capacity of 2.5 L; put the material crucible in a furnace chamber of the microwave heating device; close the furnace body and the connecting pipes of each part; and check the air-tightness.

(10) Step 2: After checking, while ensuring the sealing, turn off the gas intake valve of the furnace top; start a vacuum pump to pump air until the pressure of the system is lower than 1,000 Pa.

(11) Step 3: After the pressure of the system is lower than 1,000 Pa, start the microwave heating device to increase the temperature to 900 C. at a rate of 20 C. per minute; open the valve of the nitrogen protective gas; introduce a nitrogen gas flow at a rate of 1 liter per minute; stop heating after the reaction continues for 3 hours at a constant temperature; introduce a nitrogen gas flow again to cool the furnace to the room temperature.

(12) Step 4: After stopping the vacuum state, open the furnace cover; take out the material crucible; take out and weigh the residue, and obtain 872 g of the residue; after analysis, calculate the germanium content in the residue as 0.041%, the residual rate of germanium as 3.54%, and the volatilization rate of the secondary residue as 96.46%.

(13) Step 5: Start the setting and collecting chamber and the bag-type dust collecting chamber to collect the set volatiles; combine the obtained volatiles, weigh the same and obtain 27.62 g of the residue; calculate the germanium content in the volatiles as 35.03% and the germanium recovery rate as 95.79%.

(14) Step 6: Add industrial hydrochloric acid of 10 mol/L and of 4 times of the weight of the obtained germanium concentrates, i.e., 110.48 g, and add water of the same weight of the obtained germanium concentrates, i.e., 27.62 g to the high germanium content germanium concentrates obtained according to the above process; mix the mixture uniformly; and perform distillation and separation to obtain GeCl.sub.4.

(15) The germanium concentrate vacuum enrichment apparatus used in this process comprises: a microwave heating system 1, a setting and collecting system 2, a bag-type dust collecting system 3, an exhaust absorbing system 4, a vacuum system 5, an inert gas protecting system 6 and a water cooling system 7.

(16) The microwave heating system 1 comprises: a microwave generator 1-1, a heating chamber 1-2, a material crucible 1-3, a material supplying and discharging device 1-4, a water-cooled vacuum-sealed flange 7-1 and the inert gas protecting system 6. The materials are placed in the material crucible 1-3 which is placed in the heating chamber 1-2; the microwave generator 1-1 encloses the whole heating chamber 1-2; the inert gas protecting system 6 communicates with the heating chamber 1-2; the water-cooled vacuum-sealed flange 7-1 is provided between the heating chamber 1-2 and the microwave generator 1-1.

(17) The heating chamber 1-2 is connected to the setting and collecting system 2 via a pipe on which the water-cooled vacuum-sealed flange 7-1 is provided; a setting and collecting chamber is configured to set large particles in a gas stream, which enters a setting and collecting container 2-1; fine particles with a high germanium content enters the bag-type dust collecting system 3 along with a carrier gas.

(18) After filtering by the bag-type dust collecting system 3, a germanium enrichment product - - - rough germanium oxide is collected; the exhaust is absorbed by a weak alkali solution in the exhaust absorbing system 4 and then discharged; the bag-type dust collecting system 3 is also provided with the water-cooled vacuum-sealed flange 7-1 for cooling the same.

(19) The vacuum system 5 is provided at a tail end of the apparatus; and the whole apparatus is in a vacuum state by a vacuum valve 5-1 and a mechanical pump 5-2 working together.

(20) Compared with volatilization under a normal pressure, volatilization under a vacuum state in the embodiment has better volatilization effects, which is listed in Table 2 as below:

(21) TABLE-US-00002 TABLE 2 Germanium Residue Content Germanium Sample Germanium Volatilization Volatilization after after Volatilization Weight Content Temperature Volatilization Time Volatilization Volatilization Rate No. (g) (%) ( C.) Manner (hour(s)) (g) (%) (%) 1 10.0 1.00 900 Volatilization 3 9.09 1.09 0.92 under a normal pressure 2 10.0 1.00 900 Volatilization 3 9.03 1.1 0.67 under a normal pressure 3 10.0 1.00 1,000 Volatilization 3 8.97 0.82 26.45 under a normal pressure 4 10.0 1.00 1,000 Volatilization 3 8.0 0.83 33.60 under a normal pressure 5 10.0 1.00 1,050 Volatilization 3 8.89 0.53 52.88 under a normal pressure 6 10.0 1.00 1,050 Volatilization 3 8.86 0.53 53.04 under a normal pressure 7 10.0 1.00 1,200 Volatilization 3 8.96 0.2 82.08 under a normal pressure 8 10.0 1.00 1,200 Volatilization 3 8.93 0.2 82.14 under a normal pressure 1 2.0 1.00 900 Volatilization 0.5 1.54 0.15 88.45 under a vacuum state 2 3.6 1.00 1,100 Volatilization 0.5 2.15 0.041 97.55 under a vacuum state

(22) Table 2 shows that: 1) only when the volatilization temperature reaches 1,200 C. under the normal temperature and normal pressure, can a volatilization rate of 82% or more be reached, whereas in a vacuum state and at a temperature of 900 C., a volatilization rate of 88% or more can be reached, so the volatilization temperature is reduced by at least 300 C. compared with the first case; 2) the volatilization speed is fast under the vacuum state, and the volatilization time is reduced from 3 hours to 0.5 hour.

Embodiment 2

(23) Another method for secondary enrichment and recovery of germanium from low-grade lignite germanium concentrates by microwave heating in vacuum includes the following steps. The germanium concentrate shown in Table 1 is used as the raw material.

(24) TABLE-US-00003 TABLE 1 Main Chemical Composition of Germanium Concentrates Composition Loss on Ge SiO.sub.2 Fe.sub.2O.sub.3 Al.sub.2O.sub.3 As CaO MgO S Ignition Content, % 0.5-3.0 60-70 4-10 10-15 0.1-0.3 2-5 1-2 1-2.0 12.10

(25) Step 1: Weigh 1,000 g of germanium concentrates with a germanium content of 1.01%, and put the same into a high alumina crucible having a capacity of 2.5 L; put the material crucible in a furnace chamber of the microwave heating device; close the furnace body and the connecting pipes of each part; and check the air-tightness.

(26) Step 2: After checking, while ensuring the sealing, turn off the gas intake valve of the furnace top; start a vacuum pump to pump air until the pressure of the system is lower than 1,000 Pa.

(27) Step 3: After the pressure of the system is lower than 1,000 Pa, start the microwave heating device to increase the temperature to 1,000 C. at a rate of 50 C. per minute; open the valve of the nitrogen protective gas; introduce a nitrogen gas flow at a rate of 3 liters per minute; stop heating after the reaction continues for 2 hours at a constant temperature; introduce a nitrogen gas flow again to cool the furnace to the room temperature.

(28) Step 4: After stopping the vacuum state, open the furnace cover; take out the material crucible; take out and weigh the residue, and obtain 895 g of the residue; after analysis, calculate the germanium content in the residue as 0.027%, the residual rate of germanium as 4.24%, and the volatilization rate of the secondary residue as 95.76%.

(29) Step 5: Start the setting and collecting chamber and the bag-type dust collecting chamber to collect the set volatiles; combine the obtained volatiles, weigh the same and obtain 21.37 g of the residue; calculate the germanium content in the volatiles as 25.34% and the germanium recovery rate as 95.01%.

(30) Step 6: Add industrial hydrochloric acid of 10 mol/L and of 5 times of the weight of the obtained germanium concentrates, i.e., 106.85 g, and add water of the same weight of the obtained germanium concentrates, i.e., 21.37 g to the high germanium content germanium concentrates obtained according to the above process; mix the mixture uniformly; and perform distillation and separation to obtain GeCl.sub.4.

Embodiment 3

(31) A still another method for secondary enrichment and recovery of germanium from low-grade lignite germanium concentrates with microwave heating in vacuum includes the following steps. The germanium concentrate shown in Table 1 is used as the raw material.

(32) TABLE-US-00004 TABLE 1 Main Chemical Composition of Germanium Concentrates Composition Loss on Ge SiO.sub.2 Fe.sub.2O.sub.3 Al.sub.2O.sub.3 As CaO MgO S Ignition Content, % 0.5-3.0 60-70 4-10 10-15 0.1-0.3 2-5 1-2 1-2.0 12.10

(33) Step 1: Weigh 1,000 g of germanium concentrates with a germanium content of 2.36%, and put the same into a high alumina crucible having a capacity of 2.5 L; put the material crucible in a furnace chamber of the microwave heating device; close the furnace body and the connecting pipes of each part; and check the air-tightness.

(34) Step 2: After checking, while ensuring the sealing, turn off the gas intake valve of the furnace top; start a vacuum pump to pump air until the pressure of the system is lower than 1,000 Pa.

(35) Step 3: After the pressure of the system is lower than 1,000 Pa, start the microwave heating device to increase the temperature to 1,100 C. at a rate of 30 C. per minute; open the valve of the nitrogen protective gas; introduce a nitrogen gas flow at a rate of 2 liters per minute; stop heating after the reaction continues for 1 hour at a constant temperature; introduce a nitrogen gas flow again to cool the furnace to the room temperature.

(36) Step 4: After stopping the vacuum state, open the furnace cover; take out the material crucible; take out and weigh the residue, and obtain 899 g of the residue; after analysis, calculate the germanium content in the residue as 0.049%, the residual rate of germanium as 1.87%, and the volatilization rate of the secondary residue as 98.13%.

(37) Step 5: Start the setting and collecting chamber and the bag-type dust collecting chamber to collect the set volatiles; combine the obtained volatiles, weigh the same and obtain 45.63 g of the residue; calculate the germanium content in the volatiles as 50.93% and the germanium recovery rate as 98.47%.

(38) Step 6: Add industrial hydrochloric acid of 10 mol/L and of 4 times of the weight of the obtained germanium concentrates, i.e., 182.52 g, and add water of the same weight of the obtained germanium concentrates, i.e., 45.63 g to the high germanium content germanium concentrates obtained according to the above process; mix the mixture uniformly; and perform distillation and separation to obtain GeCl.sub.4.