Detailed Description
Referring to fig. 1, the method for wet desulfurization of sulfur-containing bauxite provided by the embodiment of the invention comprises the following steps:
Step 1) adding bauxite and sulfuric acid solution with pH value of 1-5 into an autoclave liner.
The bauxite is sedimentary bauxite of Guangxi Zhuang autonomous region, the bauxite is not weathered, the phase composition of the bauxite is complex, the sulfur content of the ore is high, the sulfur element of the bauxite mainly exists in the form of associated sulfide ore, and the associated sulfide ore is mainly pyrite. The mineral composition of the composite material mainly comprises 65 to 75 percent of diaspore, less than 0.5 percent of gibbsite, 20 to 25 percent of chlorite and clay mineral, less than 0.5 percent of muscovite, 2to 3 percent of anatase, a small amount of limonite and the like.
Referring to fig. 2, the desulfurization device for wet desulfurization of bauxite containing sulfur of the invention comprises a reaction kettle, an oxygen and nitrogen supply steel bottle connected with the reaction kettle, and a reaction kettle controller connected with the reaction kettle, wherein the reaction kettle is provided with a stirrer and a pressure gauge which are respectively used for stirring materials in the reaction kettle and detecting air pressure in the reaction kettle in real time, and meanwhile, the reaction kettle is also connected with a cooling device which is used for cooling a stirring bearing of the stirrer and cooling the reaction kettle by cooling water. Wherein, as a specific embodiment of the invention, the reaction kettle is a KCFD1-10 high-pressure reaction kettle, the maximum volume of the reaction kettle is 1000 mL, the maximum pressure is 6.0 MPa, the reaction kettle is connected by adopting a flange, and the reaction kettle is heated by an external electric furnace, and the limit temperature is 300 ℃.
In order to facilitate the subsequent oxidative leaching, the sulfur-containing bauxite requires a grinding treatment of the bauxite to a bauxite powder having a particle size of 32 μm to 37 μm prior to loading into the autoclave.
When the initial sulfuric acid consumption is gradually increased, the desulfurization rate of the sulfur-containing bauxite is increased, the pH value of the solution after the reaction is gradually reduced, and the dissolution amount of Al 2O3 is increased. Therefore, increasing the initial sulfuric acid consumption is beneficial to removing sulfur in the sulfur-containing bauxite, the oxidation-reduction equilibrium potential of oxygen under the acidic condition is larger, and the sulfur in the bauxite is more easily oxidized. However, increasing the sulfuric acid consumption increases the concentration of residual acid in the solution, which not only puts higher demands on the reaction equipment, but also increases the cost of neutralizing the acidic wastewater, so that the quality of the sulfuric acid in the sulfuric acid solution is controlled to be 1.63 g/1-16300 g/1t bauxite.
When the liquid-solid ratio is reduced, the desulfurization rate of the sulfur-containing bauxite is slightly reduced from a high level, the pH value is gradually reduced, and the dissolution amount of Al 2O3 is increased. Therefore, increasing the liquid-solid ratio can lead to the reduction of the desulfurization effect in the sulfur-containing bauxite, and simultaneously can increase the residual acid content of the treated liquid, so that the pH of the solution is reduced, and the dissolution amount of Al 2O3 is increased after the concentration of sulfuric acid in unit volume is increased, thereby increasing the treatment cost. Therefore, the liquid-solid ratio of the sulfuric acid solution to bauxite is controlled to be 500:10-500:400.
In a specific embodiment of the present invention, in order to control the dissolution amount of Al 2O3 in treated bauxite to 5% or less and to maintain the desulfurization rate to 80% or more, the sulfuric acid mass in the sulfuric acid solution is controlled to 163.3g/1t bauxite, and the liquid-solid ratio of the sulfuric acid solution to bauxite is controlled to 500:150.
And 2) slowly shaking the autoclave liner, covering the autoclave liner, uniformly sealing the autoclave liner with force, opening a nitrogen steel cylinder, introducing nitrogen into the autoclave liner, flushing the autoclave liner, and discharging air in the sealed autoclave liner.
Step 3) setting a target heating temperature, and heating and stirring to obtain a mixed material of bauxite and sulfuric acid solution. Specifically, a temperature controller is started, the experimental target temperature is set, the mixture of bauxite and sulfuric acid solution is heated, then a stirrer is started to stir the mixture of bauxite and sulfuric acid solution, the rotating speed is controlled at a set value, and meanwhile, stirring shaft cooling water of a cooling device is started to cool a stirring bearing.
Since S in sulfur-containing bauxite is mainly in the form of FeS 2 in bauxite minerals, feS 2 generates S, H 2SO4 and Fe 3+ according to formula 1 or formula 2 when high sulfur bauxite is subjected to pressure oxidation treatment, and the generated H 2SO4 reduces the pH of the desulfurization solution, so that Al 2O3 in bauxite is gradually dissolved in the solution, and Al 2O3 is dissolved.
(1)
(2)
When the desulfurization temperature is gradually increased, the removal rate of S in the treated bauxite is gradually increased, the pH value is gradually reduced, and the dissolution amount of Al 2O3 is increased. And, because the melting point of elemental sulfur is 119 ℃, when the reaction temperature exceeds the melting point of sulfur, the generated sulfur is liquid elemental sulfur, the melted liquid sulfur has poor viscosity and fluidity, and the adhesion of surrounding minerals reduces the reaction area, resulting in a reduction in desulfurization rate. Therefore, increasing the reaction temperature during desulfurization is advantageous for removing S in high-sulfur bauxite, reducing the residual sulfur content in slag components, but increasing the acidity of the treated solution increases the dissolution rate of Al 2O3. Therefore, the target heating temperature is set to 80 to 240 ℃.
In one embodiment of the present invention, the target heating temperature is preferably controlled to 150 ℃ in order to control the dissolution amount of Al 2O3 in the treated bauxite to 5% or less and to maintain the desulfurization rate to 80% or more.
And 4) continuously introducing oxygen into the autoclave liner through an oxygen steel cylinder when the target heating temperature reaches 80-240 ℃, and adjusting the pressure of the autoclave to a required value, wherein the pressure P Total (S) of the autoclave is the sum of the pressure P Oxygen gas of the oxygen and the pressure P Steam generation of water vapor in the autoclave. The oxidation leaching reaction is carried out according to a preset heat preservation time, and the reaction temperature in the autoclave is maintained by cooling water by a cooling device and electric heating in the heat preservation process, so that the fluctuation range of the reaction temperature in the autoclave is controlledWithin 2 ℃.
When oxygen is continuously introduced into the autoclave, when the partial pressure of oxygen is gradually increased, the desulfurization rate of the sulfur-containing bauxite is gradually increased, but basically kept unchanged after the desulfurization rate is increased to a certain value, the pH value is gradually reduced, and the dissolution amount of Al 2O3 is increased. Therefore, the improvement of the oxygen partial pressure during desulfurization is beneficial to the S removal in the high-sulfur bauxite, reduces the residual sulfur content in slag components, but increases the acidity of the treated solution, thereby increasing the dissolution amount of Al 2O3. After the oxygen partial pressure is increased, the concentration of dissolved oxygen in the solution is increased, and the concentration of the reactant is increased, so that the forward movement of the reaction balance of the associated mineral pyrite is facilitated, and the oxidation rate of elemental sulfur is improved. In addition, in the pyrite pressure oxidation process, along with the generation of elemental sulfur, the increase of oxygen partial pressure can further oxidize the elemental sulfur into sulfate, and the dispersion of product sulfur can be fast to a certain extent. Therefore, after continuously introducing oxygen into the autoclave liner, the oxygen partial pressure was maintained at 0.1MPa to 0.8Mpa.
In a specific embodiment of the present invention, in order to control the dissolution amount of Al 2O3 in treated bauxite to 5% or less and to maintain the desulfurization rate to 80% or more, oxygen is continuously introduced into the autoclave liner and then the oxygen partial pressure is maintained at 0.5Mpa.
When the heat preservation time is increased, the desulfurization rate of the sulfur-containing bauxite is increased, the sulfur-containing bauxite basically keeps unchanged after the desulfurization rate is increased to a certain degree, the pH value is gradually reduced, and the dissolution quantity of Al 2O3 is increased. Therefore, the prolonging of the heat preservation time is beneficial to improving the desulfurization rate of the sulfur bauxite, but the heat preservation time of heating is controlled to be 60 min-180 min in consideration of the comprehensive desulfurization effect and time cost.
In one embodiment of the present invention, the heating time is controlled to be 120min in order to control the dissolution amount of Al 2O3 in the treated bauxite to 5% or less and to maintain the desulfurization rate to 80% or more.
And 5) stopping heating and closing an air inlet of the autoclave after the oxidation leaching reaction reaches the target time, dismantling auxiliary devices such as a transmission device, a temperature measuring device and a speed measuring device of the desulfurization device, introducing cooling water to cool the autoclave, and opening an air outlet of the autoclave to completely discharge the gas in the autoclave liner after the temperature in the autoclave is reduced to below 50 ℃. Then opening the kettle cover, taking out the kettle liner, and filtering out leached slurry in the high-pressure kettle liner by adopting a vacuum pump.
And 6) filtering the slurry, repeatedly washing filter residues, cooling to room temperature, and putting the filter residues into a drying oven for drying to obtain the desulfurized bauxite.
The method for wet desulfurization of sulfur-containing bauxite provided by the invention is further described below by referring to specific examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. The experimental procedures, which are not specified in the following examples, are generally determined according to national standards. If the corresponding national standard does not exist, the method is carried out according to the general international standard, the conventional condition or the condition recommended by the manufacturer.
Example 1
(1) Adding the grinded bauxite powder with the granularity of 35 mu m into an autoclave liner, adding a sulfuric acid solution with the PH of 3 into the autoclave liner according to the adding amount of the bauxite with the sulfuric acid mass of 163 g/1t in the sulfuric acid solution, and controlling the liquid-solid ratio of the mixed materials to be 500:100.
(2) Slowly shaking the autoclave liner, covering the autoclave liner with a cover, uniformly sealing the autoclave liner with force, then opening a nitrogen steel bottle, introducing nitrogen into the autoclave to flush the autoclave liner, and discharging air in the sealed autoclave liner.
(3) And starting a temperature controller, setting the target heating temperature to be 100 ℃, starting to heat the mixture of the bauxite and the sulfuric acid solution, starting a stirrer to stir the mixture of the bauxite and the sulfuric acid solution, controlling the rotating speed to be a set value, and simultaneously starting stirring shaft cooling water of a cooling device to cool a stirring bearing.
(4) When the target heating temperature reaches 100 ℃, oxygen is continuously introduced into the inner container of the high-pressure kettle through an oxygen steel bottle, and the oxygen partial pressure in the high-pressure kettle is adjusted to be 0.6 MPa. The preset heat preservation time is 120min, the oxidation leaching reaction is carried out, and meanwhile, the reaction temperature in the autoclave is maintained by cooling water and electric heating by a cooling device in the heat preservation process, so that the fluctuation range of the reaction temperature in the autoclave is controlledWithin 2 ℃.
(5) After the oxidation leaching reaction reaches 120 min, stopping heating and closing the air inlet of the autoclave, dismantling the transmission device, the temperature measuring device, the speed measuring device and other auxiliary devices of the desulfurization device, introducing cooling water to cool the autoclave, and opening the air outlet of the autoclave to completely discharge the gas in the kettle liner after the temperature in the autoclave is reduced to below 50 ℃. Then opening the kettle cover, taking out the kettle liner, and filtering out leached slurry in the high-pressure kettle liner by adopting a vacuum pump.
(6) Filtering the slurry, repeatedly washing filter residues, cooling to room temperature, and drying the filter residues in a drying oven to obtain the desulfurized bauxite.
The pH of the solution after the reaction, the sulfur removal rate of bauxite after desulfurization and the dissolution rate of Al 2O3 in this example are shown in Table 1.
TABLE 1
Examples |
PH after reaction |
S Removal rate /% |
Al2O3 Amount of dissolution /% |
Example 1 |
5.78 |
82.26 |
3.72 |
Example 2 |
4.56 |
86.36 |
4.26 |
Example 3 |
1.05 |
85.56 |
2.77 |
Example 4 |
0.68 |
88.61 |
3.12 |
Example 5 |
0.75 |
86.47 |
4.08 |
From the data of the PH of the solution after reaction, the sulfur removal rate of the bauxite after desulfurization, the dissolution rate of Al 2O3 and the like in the table 1, the wet desulfurization method for the sulfur-containing bauxite provided by the embodiment of the invention can greatly reduce the sulfur content in the sulfur-containing bauxite, and obtain a good desulfurization effect, thereby improving the comprehensive utilization rate of the bauxite.
Example 2
(1) Adding the ground bauxite powder with the granularity of 32 mu m into an autoclave liner, adding a sulfuric acid solution with the PH of 1 into the autoclave liner according to the addition amount of the bauxite with the sulfuric acid mass of 16.3 g/1t in the sulfuric acid solution, and controlling the liquid-solid ratio of the mixed materials to be 500:200.
(2) Slowly shaking the autoclave liner, covering the autoclave liner with a cover, uniformly sealing the autoclave liner with force, then opening a nitrogen steel bottle, introducing nitrogen into the autoclave to flush the autoclave liner, and discharging air in the sealed autoclave liner.
(3) And starting a temperature controller, setting the target heating temperature to be 80 ℃, starting to heat the mixture of the bauxite and the sulfuric acid solution, starting a stirrer to stir the mixture of the bauxite and the sulfuric acid solution, controlling the rotating speed to be a set value, and simultaneously starting stirring shaft cooling water of a cooling device to cool a stirring bearing.
(4) When the target heating temperature reaches 80 ℃, oxygen is continuously introduced into the inner container of the high-pressure kettle through an oxygen steel bottle, and the oxygen partial pressure in the high-pressure kettle is adjusted to be 0.8 MPa. The preset heat preservation time is 180 min, the oxidation leaching reaction is carried out, and meanwhile, the reaction temperature in the autoclave is maintained by cooling water and electric heating by a cooling device in the heat preservation process, so that the fluctuation range of the reaction temperature in the autoclave is controlledWithin 2 ℃.
(5) After the oxidation leaching reaction reaches 180 min, stopping heating and closing the air inlet of the autoclave, dismantling the transmission device, the temperature measuring device, the speed measuring device and other auxiliary devices of the desulfurization device, introducing cooling water to cool the autoclave, and opening the air outlet of the autoclave to completely discharge the gas in the kettle liner after the temperature in the autoclave is reduced to below 50 ℃. Then opening the kettle cover, taking out the kettle liner, and filtering out leached slurry in the high-pressure kettle liner by adopting a vacuum pump.
(6) Filtering the slurry, repeatedly washing filter residues, cooling to room temperature, and drying the filter residues in a drying oven to obtain the desulfurized bauxite.
The pH of the solution after the reaction, the sulfur removal rate of bauxite after desulfurization and the dissolution rate of Al 2O3 in this example are shown in Table 1.
From the data of the PH of the solution after reaction, the sulfur removal rate of the bauxite after desulfurization, the dissolution rate of Al 2O3 and the like in the table 1, the wet desulfurization method for the sulfur-containing bauxite provided by the embodiment of the invention can greatly reduce the sulfur content in the sulfur-containing bauxite, and obtain a good desulfurization effect, thereby improving the comprehensive utilization rate of the bauxite.
Example 3
(1) Adding the ground bauxite powder with the granularity of 37 mu m into an autoclave liner, adding a sulfuric acid solution with the PH of 5 into the autoclave liner according to the adding amount of 1630g/1t bauxite in the sulfuric acid solution, and controlling the liquid-solid ratio of the mixed materials to be 500:400.
(2) Slowly shaking the autoclave liner, covering the autoclave liner with a cover, uniformly sealing the autoclave liner with force, then opening a nitrogen steel bottle, introducing nitrogen into the autoclave to flush the autoclave liner, and discharging air in the sealed autoclave liner.
(3) And starting a temperature controller, setting the target heating temperature to 240 ℃, starting to heat the mixture of the bauxite and the sulfuric acid solution, starting a stirrer to stir the mixture of the bauxite and the sulfuric acid solution, controlling the rotating speed to be a set value, and simultaneously starting stirring shaft cooling water of a cooling device to cool a stirring bearing.
(4) When the target heating temperature reaches 240 ℃, oxygen is continuously introduced into the inner container of the autoclave through an oxygen steel bottle, and the oxygen partial pressure in the autoclave is adjusted to be 0.4 MPa. The preset heat preservation time is 60 min, the oxidation leaching reaction is carried out, and meanwhile, the reaction temperature in the autoclave is maintained by cooling water and electric heating of a cooling device in the heat preservation process, so that the fluctuation range of the reaction temperature in the autoclave is controlledWithin 2 ℃.
(5) After the oxidation leaching reaction reaches 60 minn, stopping heating and closing the air inlet of the autoclave, dismantling the transmission device, the temperature measuring device, the speed measuring device and other auxiliary devices of the desulfurization device, introducing cooling water to cool the autoclave, and opening the air outlet of the autoclave to completely discharge the gas in the kettle liner after the temperature in the autoclave is reduced to below 50 ℃. Then opening the kettle cover, taking out the kettle liner, and filtering out leached slurry in the high-pressure kettle liner by adopting a vacuum pump.
(6) Filtering the slurry, repeatedly washing filter residues, cooling to room temperature, and drying the filter residues in a drying oven to obtain the desulfurized bauxite.
The pH of the solution after the reaction, the sulfur removal rate of bauxite after desulfurization and the dissolution rate of Al 2O3 in this example are shown in Table 1.
From the data of the PH of the solution after reaction, the sulfur removal rate of the bauxite after desulfurization, the dissolution rate of Al 2O3 and the like in the table 1, the wet desulfurization method for the sulfur-containing bauxite provided by the embodiment of the invention can greatly reduce the sulfur content in the sulfur-containing bauxite, and obtain a good desulfurization effect, thereby improving the comprehensive utilization rate of the bauxite.
Example 4
(1) Adding the grinded bauxite powder with the granularity of 36 mu m into an autoclave liner, adding a sulfuric acid solution with the PH of 1-5 into the autoclave liner according to the adding amount of the bauxite with the sulfuric acid mass of 163.3 in the sulfuric acid solution, and controlling the liquid-solid ratio of the mixed materials to be 500:150.
(2) Slowly shaking the autoclave liner, covering the autoclave liner with a cover, uniformly sealing the autoclave liner with force, then opening a nitrogen steel bottle, introducing nitrogen into the autoclave to flush the autoclave liner, and discharging air in the sealed autoclave liner.
(3) And starting a temperature controller, setting the target heating temperature to be 150 ℃, starting to heat the mixture of the bauxite and the sulfuric acid solution, starting a stirrer to stir the mixture of the bauxite and the sulfuric acid solution, controlling the rotating speed to be a set value, and simultaneously starting stirring shaft cooling water of a cooling device to cool a stirring bearing.
(4) When the target heating temperature reaches 150 ℃, oxygen is continuously introduced into the inner container of the high-pressure kettle through an oxygen steel bottle, and the oxygen partial pressure in the high-pressure kettle is adjusted to be 0.5 MPa. The preset heat preservation time is 120 min, the oxidation leaching reaction is carried out, and meanwhile, the reaction temperature in the autoclave is maintained by cooling water and electric heating by a cooling device in the heat preservation process, so that the fluctuation range of the reaction temperature in the autoclave is controlledWithin 2 ℃.
(5) After the oxidation leaching reaction reaches 120 min, stopping heating and closing the air inlet of the autoclave, dismantling the transmission device, the temperature measuring device, the speed measuring device and other auxiliary devices of the desulfurization device, introducing cooling water to cool the autoclave, and opening the air outlet of the autoclave to completely discharge the gas in the kettle liner after the temperature in the autoclave is reduced to below 50 ℃. Then opening the kettle cover, taking out the kettle liner, and filtering out leached slurry in the high-pressure kettle liner by adopting a vacuum pump.
(6) Filtering the slurry, repeatedly washing filter residues, cooling to room temperature, and drying the filter residues in a drying oven to obtain the desulfurized bauxite.
The pH of the solution after the reaction, the sulfur removal rate of bauxite after desulfurization and the dissolution rate of Al 2O3 in this example are shown in Table 1.
From the data of the PH of the solution after reaction, the sulfur removal rate of the bauxite after desulfurization, the dissolution rate of Al 2O3 and the like in the table 1, the wet desulfurization method for the sulfur-containing bauxite provided by the embodiment of the invention can greatly reduce the sulfur content in the sulfur-containing bauxite, and obtain a good desulfurization effect, thereby improving the comprehensive utilization rate of the bauxite.
Example 5
(1) Adding the ground bauxite powder with the granularity of 34 mu m into an autoclave liner, adding a sulfuric acid solution with the PH of 1-5 into the autoclave liner according to the adding amount of 1630g/1t bauxite in the sulfuric acid solution, and controlling the liquid-solid ratio of the mixed materials to be 500:300.
(2) Slowly shaking the autoclave liner, covering the autoclave liner with a cover, uniformly sealing the autoclave liner with force, then opening a nitrogen steel bottle, introducing nitrogen into the autoclave to flush the autoclave liner, and discharging air in the sealed autoclave liner.
(3) And starting a temperature controller, setting the target heating temperature to be 200 ℃, starting to heat the mixture of the bauxite and the sulfuric acid solution, starting a stirrer to stir the mixture of the bauxite and the sulfuric acid solution, controlling the rotating speed to be a set value, and simultaneously starting stirring shaft cooling water of a cooling device to cool a stirring bearing.
(4) When the target heating temperature reaches 200 ℃, oxygen is continuously introduced into the inner container of the high-pressure kettle through an oxygen steel bottle, and the oxygen partial pressure in the high-pressure kettle is adjusted to be 0.3 MPa. The preset heat preservation time is 90 min, the oxidation leaching reaction is carried out, and meanwhile, the reaction temperature in the autoclave is maintained by cooling water and electric heating of a cooling device in the heat preservation process, so that the fluctuation range of the reaction temperature in the autoclave is controlledWithin 2 ℃.
(5) After the oxidation leaching reaction reaches 90 min, stopping heating and closing the air inlet of the autoclave, dismantling the transmission device, the temperature measuring device, the speed measuring device and other auxiliary devices of the desulfurization device, introducing cooling water to cool the autoclave, and opening the air outlet of the autoclave to completely discharge the gas in the kettle liner after the temperature in the autoclave is reduced to below 50 ℃. Then opening the kettle cover, taking out the kettle liner, and filtering out leached slurry in the high-pressure kettle liner by adopting a vacuum pump.
(6) Filtering the slurry, repeatedly washing filter residues, cooling to room temperature, and drying the filter residues in a drying oven to obtain the desulfurized bauxite.
The pH of the solution after the reaction, the sulfur removal rate of bauxite after desulfurization and the dissolution rate of Al 2O3 in this example are shown in Table 1.
From the data of the PH of the solution after reaction, the sulfur removal rate of the bauxite after desulfurization, the dissolution rate of Al 2O3 and the like in the table 1, the wet desulfurization method for the sulfur-containing bauxite provided by the embodiment of the invention can greatly reduce the sulfur content in the sulfur-containing bauxite, and obtain a good desulfurization effect, thereby improving the comprehensive utilization rate of the bauxite.
Finally, it should be noted that the above-mentioned embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications and equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention, and all such modifications and equivalents are intended to be encompassed in the scope of the claims of the present invention.