CN113289761B - Pressurized dissolved air size mixing device and method based on interface micro-nano bubbles - Google Patents
Pressurized dissolved air size mixing device and method based on interface micro-nano bubbles Download PDFInfo
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Abstract
The invention discloses a pressurized dissolved air size mixing device and a pressurized dissolved air size mixing method based on interface micro-nano bubbles, wherein the size mixing device comprises: the device comprises a stirring barrel, an interface micro-nano bubble controller and an air compressor; an air inlet of the stirring barrel is communicated with an air outlet of the air compressor through an air inlet pipe, and an ore outlet of the stirring barrel is communicated with an ore inlet of the interface micro-nano bubble controller through an ore outlet pipe. The invention provides a pressurized gas dissolving device and method based on interface micro-nano bubbles regulation and control, according to the priority of micro-nano bubbles to be separated out on the surface of a rough and hydrophobic mineral, the content of dissolved gas in ore pulp is respectively increased through different pressurized gas dissolving methods, so that more interface micro-nano bubbles can be separated out more quickly and selectively under the condition of sudden pressure drop of the ore pulp, the difference of interface hydrophobicity among minerals can be rapidly expanded, the size of equipment is reduced, the field space utilization rate is improved, and the ore dressing cost is further reduced.
Description
Technical Field
The invention relates to the technical field of mineral processing, in particular to a pressurized dissolved air size mixing device and method based on interface micro-nano bubbles.
Background
Mineral resources are an important foundation for the development of national socioeconomic performance, and have an absolutely irreplaceable status particularly in industry. At present, the primary separation and purification of ores are mainly performed by a flotation method, and the flotation is usually froth flotation, which utilizes the differences of the physical and chemical properties of ore interfaces to realize mineral separation, wherein the wettability (hydrophilic and hydrophobic properties) of mineral surfaces has a decisive effect on the separation and purification effect of minerals. Therefore, it is particularly important to improve the difference in wettability of the mineral surface. At present, the difference of the mineral surface wettability is mainly increased industrially by adding various agents, and the difference of the surface wettability of various minerals in the ore pulp treated by the flotation agents becomes more obvious, so that mineral particles can be selectively attached to the surfaces of air bubbles, and separation and purification can be realized. However, a great amount of chemical agents are used, which has a great pollution risk to the environment, and along with the increasing demand of minerals and the gradual change of mineral properties to 'poor, fine and miscellaneous', the dosage of the agents is also continuously increased, and according to statistics, the annual consumption of beneficiation agents in China is in megaton level, which leads to the continuous increase of beneficiation cost.
The method has the advantages that the difference of the properties of mineral interfaces is enlarged, the separation efficiency is improved, and the cost is reduced, so that the method is a popular research direction for many scholars, however, the current research mainly focuses on flotation reagents, solution properties, ore dressing processes and equipment, and little research is needed on the pretreatment and size mixing of minerals before flotation and the change of the difference of the hydrophobicity of the mineral interfaces by using micro-nano bubbles. Under the pressure drop, interface micro-nano bubbles are generated by the diffusion phenomenon caused by the concentration difference of the dissolved gas in the liquid, and the interface micro-nano bubbles are easier to generate on a rough hydrophobic surface, so that the aim of modifying the interface hydrophobicity is fulfilled. However, because the content of the dissolved gas in the ore pulp is limited, the generation amount of micro-nano bubbles at the interface is less due to insufficient content of the dissolved gas in the ore pulp with higher concentration, and the hydrophobicity of the mineral interface cannot be sufficiently and selectively modified; on the other hand, because the content of dissolved gas is insufficient, a large amount of micro-nano bubbles can not be rapidly generated on the surface of the hydrophobic rough mineral, and the time for the difference of the surface areas of the micro-nano bubbles on the interface between the target mineral and the gangue mineral to reach the optimal state is long, so that the regulation and control equipment is too large, and the actual field application is not facilitated.
Disclosure of Invention
In view of the above, it is necessary to provide a pressurized dissolved air slurry mixing apparatus and method based on interface micro-nano bubbles, so as to solve the technical problems in the prior art that when the micro-nano bubbles are used for changing the difference of the mineral interface hydrophobicity in ore pulp with higher concentration, the hydrophobic modification effect is poor due to insufficient dissolved air content, and the equipment is too large due to too long regulation and control time.
The first aspect of the invention provides a pressurized dissolved air slurry mixing device based on interface micro-nano bubbles, which comprises: the device comprises a stirring barrel, an interface micro-nano bubble controller and an air compressor; an air inlet of the stirring barrel is communicated with an air outlet of the air compressor through an air inlet pipe, and an ore outlet of the stirring barrel is communicated with an ore inlet of the interface micro-nano bubble controller through an ore outlet pipe.
The second aspect of the invention provides a pressurized dissolved air size mixing method based on interface micro-nano bubbles, which comprises the following steps:
s1, conveying air into the stirring barrel through an air compressor, and pressurizing and dissolving the ore pulp in the stirring barrel;
and S2, conveying the ore pulp subjected to the pressurized gas dissolving process to an interface micro-nano bubble controller for mineral interface hydrophobicity regulation.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a pressurized air dissolving device and method based on interface micro-nano bubbles regulation and control, which are characterized in that according to the fact that micro-nano bubbles are separated out in preference to rough and hydrophobic mineral surfaces, the content of dissolved air in ore pulp is respectively increased through different pressurized air dissolving methods, so that more interface micro-nano bubbles can be separated out more quickly and selectively under the condition that the pressure suddenly drops, the difference of interface hydrophobicity among minerals is enlarged quickly, the size of equipment is reduced, the field space utilization rate is improved, and the ore dressing cost is further reduced.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of a pressurized dissolved air slurry mixing device based on interface micro-nano bubbles provided by the invention;
FIG. 2 is a schematic view of the construction of the mixing tank of FIG. 1;
fig. 3 is a schematic structural diagram of the interface micro-nano bubble controller in fig. 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, a first aspect of the present invention provides a pressurized dissolved air slurry mixing apparatus based on interface micro-nano bubbles, including: the device comprises a stirring barrel 1, an interface micro-nano bubble controller 2 and an air compressor 3. The air inlet 118 of the stirring barrel 1 is communicated with the air outlet of the air compressor 3 through an air inlet pipe, and the ore outlet of the stirring barrel 1 is communicated with the ore inlet of the interface micro-nano bubble controller 2 through an ore outlet pipe.
The air compressor 3 is mainly used for introducing air into the stirring barrel 1 so that more dissolved gas exists in ore pulp; the stirring barrel 1 is mainly used for stirring ore pulp so as to uniformly mix materials in the ore pulp and fully dissolve air; the ore pulp is uniformly mixed and fully dissolves air and then is conveyed to the interface micro-nano bubble controller 2, so that more interface micro-nano bubbles are formed on the surface of minerals in the ore pulp after pressurized air dissolution, more interface micro-nano bubbles can be separated out by the ore pulp with different concentrations in a better selective mode under the condition of sudden pressure drop, the difference of interface hydrophobicity among minerals is rapidly enlarged, the size of equipment is reduced, the field space utilization rate is improved, and the ore dressing cost is further reduced while the ore dressing efficiency is improved.
Referring to fig. 2, the stirring barrel 1 includes a barrel 11 and a stirring mechanism 12, the stirring mechanism 12 is disposed through the barrel 11, and the stirring mechanism 12 is used for stirring the ore slurry in the barrel 11, so that each material in the ore slurry in the barrel 11 is uniformly mixed and air is fully dissolved.
Further, a slurry inlet 111 and a first outlet 112 are disposed below the lateral surface of the bucket body 11, and a second outlet 113 is disposed above the lateral surface of the bucket body 11. The ore pulp inlet 111 is communicated with an ore pulp storage tank (not shown in the figure) through an ore inlet pipe, and the first ore outlet 112 and the second ore outlet 113 are respectively communicated with the ore inlet of the interface micro-nano bubble controller 2 through an ore outlet pipe. The air inlet 118 is disposed above the tub 11, so that air in the air compressor 3 enters the tub 11 through the air inlet 118. In some embodiments of the present invention, the barrel 11 has a cylindrical upper portion and a funnel-shaped lower portion.
Further, a first ore inlet valve 114 is arranged at the ore pulp inlet 111, a first ore outlet valve 115 is arranged at the first ore outlet 112, and a second ore outlet valve 116 is arranged at the second ore outlet 113.
In the invention, the first ore feeding valve 114 is an inflow control valve for ore pulp to enter the barrel body 11; the first ore removal valve 115 is an outflow control valve for ore pulp flowing out of the stirring barrel 1; the second ore discharging valve 116 is an outflow rate of the ore slurry flowing out of the tank 11 and a balance air pressure control valve for controlling an outflow condition of the ore slurry or balancing an air pressure in the tank 11 to be a normal pressure when the ore slurry enters the tank 11, so that the ore slurry can enter the tank 11 at the normal pressure.
Further, an accidental discharge port 117 is arranged at the bottom of the barrel body 11, an accidental discharge valve is arranged at the accidental discharge port 117, and the accidental discharge port 117 is used for completely discharging ore pulp in the barrel body 11 when equipment is overhauled or faults occur; the upper end of the barrel body 11 is also provided with a chemical adding port, a water replenishing port and a pressure gauge. Further, a dosing pump and a replenishing pump are arranged at the dosing port and the replenishing port.
Further, an air inlet valve 31 is arranged between the air inlet pipe of the stirring barrel 1 and the air inlet pipe of the air compressor 3, and the air inlet valve 31 is used for regulating and controlling the inflow of air into the stirring barrel 1.
In the invention, the barrel body 11 is in a sealed state after all valves, the dosing pump and the water replenishing pump are closed.
Further, a slurry conveying pump 4 is further arranged on a mine outlet pipe between a mine outlet of the stirring barrel 1 and a mine inlet of the interface micro-nano bubble controller 2, and the slurry conveying pump 4 is used for driving materials in the stirring barrel 1 to enter the interface micro-nano bubble controller 2.
Furthermore, the first ore outlet 112 and the second ore outlet 113 are respectively communicated with an ore inlet of the slurry pump 4 through a pipeline, and an ore outlet of the slurry pump 4 is communicated with an ore inlet of the interface micro-nano bubble controller 2 through a pipeline.
In the present invention, the specific structure of the stirring mechanism 12 is not limited, and those skilled in the art can make routine selections as required. In some embodiments of the present invention, the stirring mechanism 12 includes a drive shaft 121, an impeller 122, and a power source 123. One end of the transmission shaft 122 is disposed in the tub 11 and connected to the impeller 122, and the other end of the transmission shaft 121 penetrates the tub 11 and is connected to the power source 123. Specifically, the power source 123 is a motor, and the motor drives the transmission shaft 121 through a belt. The top end of the transmission shaft 121 is provided with a bearing body 124 for ensuring the stable rotation of the transmission shaft 121.
Referring to fig. 3, the interface micro-nano bubble controller 2 includes a first tube 21, a second tube 22 and a third tube 23. The feeding end of the first pipe 21 is communicated with the ore outlet of the stirring barrel 1 through a pipeline, the discharging end of the first pipe 21 is communicated with the second pipe 22, and the inner diameter of the second pipe 22 is smaller than that of the first pipe 21; the feed end of the third pipe 23 is communicated with the discharge end of the second pipe 22 and the inner diameter of the third pipe 23 is larger than that of the second pipe 22.
In the invention, the inner diameter of the first pipe body 21 is larger than that of the second pipe body 22, and through the change of the inner diameter of the second pipe body 22, when ore pulp flows into the second pipe body 22 from the first pipe body 21, the flow rate of the ore pulp is increased, the pressure is suddenly reduced, and dissolved gas in the ore pulp is diffused under the pressure reduction effect and forms interface micro-nano bubbles on the surface of minerals; in addition, the inner diameter of the third pipe 23 is larger than that of the second pipe 22, so that after the ore pulp flows into the third pipe 23 from the second pipe 22, the flow velocity of the ore pulp is reduced, the impact force of the ore pulp is reduced, and the subsequent containing device and the collection and storage of the ore pulp are facilitated.
Further, the first tube 21 and the second tube 22 are communicated with each other through a first connecting tube 24, and the second tube 22 and the third tube 23 are communicated with each other through a second connecting tube 25. Specifically, the inner diameter of the first connecting pipe 24 is gradually reduced from one end thereof opposite to the first pipe 21 to the other end thereof, and the inner diameter of the second connecting pipe 25 is gradually increased from one end thereof opposite to the second pipe 22 to the other end thereof.
The invention realizes the smooth flow of the ore pulp between the first pipe 21 and the second pipe 22 and between the second pipe 22 and the third pipe 23 through the gradual change of the inner diameters of the first connecting pipe 24 and the second connecting pipe 25, thereby reducing the problem of overlarge flow resistance caused by the sudden change of the inner diameters.
Further, the inner diameter of the larger end of the first connecting pipe 24 is the same as the inner diameter of the first pipe 21, the inner diameter of the smaller end of the first connecting pipe is the same as the inner diameter of the second pipe 22, the inner diameter of the smaller end of the second connecting pipe 25 is the same as the inner diameter of the second pipe 22, and the inner diameter of the larger end of the second connecting pipe is the same as the inner diameter of the third pipe 23, so that smooth transition of the inner diameters among the first pipe 21, the second pipe 22 and the third pipe 23 can be realized, the resistance of ore pulp flowing is reduced to the maximum, and the stability of ore pulp flowing is improved.
Further, the lengths of the first tube 21 and the third tube 23 are both 0.1 to 2m, and the lengths of the first connecting tube 24 and the second connecting tube 25 are both 0.5 to 1 m; the ratio of the inner diameters of the first tube 21 and the second tube 22 is 1: 0.25-0.6, and the inner diameter of the second tube 22 is 0.01-0.3 m; the flow rate of the ore pulp in the second pipe 22 is 5-20 m/s, the length is 5-30 m, the pressure in the pipe is 4-101 Kpa, and the size of the generated interface micro-nano bubbles is 0.1-500 μm. In the invention, the air compressor 3 is communicated with the stirring barrel 1, so that a pressurizing and air dissolving process can be carried out, the length of the second pipe body 22 is greatly shortened on the premise of improving the flotation effect, the second pipe body 22 is reduced to 5-30 m from 5-60 m, and the floor area of equipment is saved.
The ore pulp is reduced in pipe diameter at the throat (the second pipe body 22) of the interface micro-nano controller 2, so that the pressure of the ore pulp passing through the throat is suddenly reduced, interface micro-nano bubbles are generated due to the diffusion phenomenon caused by the concentration difference of dissolved gas in liquid under the pressure sudden reduction, the interface micro-nano bubbles are easier to generate on a rough hydrophobic surface, and the hydrophobicity of the interface micro-nano bubbles is increased; introducing compressed air into the liquid under the pressurization condition, so that the air is dissolved in water to form saturated dissolved air water, and the content of the dissolved air in the water is improved; therefore, the precipitation amount of the micro-nano bubbles on the surface of the rough hydrophobic mineral in the ore pulp is increased under the condition that the pressure of the ore pulp after air dissolution is pressurized and suddenly reduced, so that the rough hydrophobic surface in the high-concentration ore pulp can also precipitate a large amount of micro-nano bubbles, the difference of the hydrophobicity of the interfaces between minerals is rapidly enlarged, the size of equipment is reduced, the field space utilization rate is improved, and the ore dressing cost is further reduced while the ore dressing efficiency is improved.
The second aspect of the invention provides a pressurized dissolved air slurry mixing method based on interface micro-nano bubbles, which comprises the following steps:
s1, conveying air into the stirring barrel 1 through the air compressor 3, and pressurizing and dissolving the ore pulp in the stirring barrel 1;
and S2, conveying the ore pulp subjected to the pressurized gas dissolving process to the interface micro-nano bubble controller 2 for mineral interface hydrophobicity regulation.
In the invention, the pressurizing and gas dissolving process is an open pressurizing and gas dissolving process or a closed pressurizing and gas dissolving process. When the required pressure in the stirring barrel 1 is 0.1-0.2 Mpa, an open type pressurizing and air dissolving process is selected; when the required pressure in the stirring barrel 1 is 0.2-0.7 Mpa, a closed type pressurizing and gas dissolving process is selected.
Specifically, the required pressure in the stirring barrel is determined according to the following method:
a1, establishing a semi-empirical formula of the change process of the surface area S of the interface micro-nano bubble along with the time t at different growth stages of the bubble, quickly entering an expansion stage due to the increase of the growth speed of the bubble after pressurization, neglecting a floating stage of constant radius growth, a transition stage of radius and contact angle change for simplifying calculation, and enabling the different stages to comprise an expansion stage of constant contact angle growth and a bubble critical desorption stage;
the surface area of the spherical-crown-shaped bubble is as follows:
S＝2πRh＝2πR 2 (1+cosθ) (1)
a model based on diffusion theory of R variation with t during the expansion phase of constant contact angle growth is as follows:
the model of desorption radius R changing with t in the critical desorption stage of bubbles based on the diffusion theory is as follows:
wherein:
in the formula: theta is the bubble contact angle, degree; r is the bubble radius, m; r d Is the critical desorption radius of the bubbles, m; d is the diffusion coefficient of dissolved gas; rho is the gas density in the mineral surface bubbles, Kg/m 3 (ii) a Delta rho is the density difference between air and liquid, Kg/m 3 (ii) a g is the acceleration of gravity, m/s 2 (ii) a P is the pressure in the mixing vessel, N/m 2 (ii) a σ is the bubble-liquid interfacial tension, N/m; c ∞ The concentration of dissolved gas at infinity, Kg/m, in the bubbles 3 ；C s In order to dissolve the gas concentration, Kg/m 3 (ii) a r is dimensionless time; t is the bubble growth time, s; a. b is constant, (t, a, b, P 2 Specific values can be determined by performing experiments according to the device and method described in patent CN202010019381.3, and combining the actual field situation).
A2, determining the pressure in the stirring barrel by combining the surface area of bubbles at the mineral interface with the Henry formula and the actual situation on site;
the henry formula is: c s ＝K H P 2 ，C ∞ ＝K H P 1 ；
In the formula: k is H Is henry constant, the value of which is affected by temperature and solution properties; c ∞ The concentration of dissolved gas at infinity, Kg/m, in the bubbles 3 ；C s In order to dissolve the gas concentration, Kg/m 3 ；P 1 Is the pressure in the mixing drum; p 2 The pressure in the second tube body of the interface micro-nano bubble controller.
Pressure P in the mixing tank 1 The determination method of (2) is as follows:
a201, P 1 The range of (A) is as follows: 0.1-0.7 Mpa to obtain C ∞ The range of (A) is as follows: 0.1K H ～0.7K H A1 is to P 1 Dividing a certain step length into a plurality of pressure values in a specified range, calculating a change curve of the radius of the bubble along with time under different pressure values by combining a formula (2), and calculating the slope of the curve through approximate processing
And calculating the critical desorption radius of the bubbles by combining the formula (3).
A202, determining the radius when the growth time T of the bubble is T according to the change curve of the radius of the bubble along with time and the critical desorption radius of the bubble: if the radius of the bubbles at the time T (the time when the ore slurry flows through the second pipeline) does not exceed the critical desorption radius, the radius of the bubbles is the radius at the time T, and if the radius exceeds the critical desorption radius, the radius of the bubbles is the critical desorption radius.
A203, calculating the surface area of the bubbles at the mineral interface by combining the determined bubble radius with the formula (1), wherein the pressure when the difference Delta S between the surface areas of the target mineral and the non-target mineral is maximum is the pressure P in the stirring barrel 1 。
Furthermore, when the open type pressurizing and gas dissolving process is used, the ore pulp is stirred and dissolved in the bucket body 11, and the fully stirred ore pulp can be discharged through the second ore outlet 113; when the required dissolved gas amount is large, the required pressure is high, a closed pressurizing and gas dissolving process is used, ore pulp is stirred in the barrel body 11, after the pressurizing and gas dissolving is finished, the ore pulp is discharged through the first ore outlet 112, and then the ore pulp is added again to be stirred, and various flotation reagents and pressurizing and gas dissolving are added.
Further, the open type pressurizing and air dissolving process specifically comprises the following steps: under the condition of stirring, the first ore inlet valve 114, the second ore outlet valve 116 and the air inlet valve 31 are opened, the first ore outlet valve 115 is closed, ore pulp enters the barrel body 11 through the ore inlet pipe, and the air compressor 3 conveys air into the barrel body 11 through the air inlet pipe.
Furthermore, in the open type pressurized gas dissolving process, the slurry directly flows out from the second ore outlet 113.
Further, the closed type pressurizing and air dissolving process specifically comprises the following steps: under the condition of stirring, the air inlet valve 31 and the first ore removal valve 115 are closed, the first ore inlet valve 114 and the second ore removal valve 116 are opened, ore pulp is added into the barrel body 11, after the ore pulp is added into the barrel body 11, the first ore inlet valve 114 and the second ore removal valve 116 are closed, the air inlet valve 31 is opened at the same time, the air compressor 3 conveys air into the barrel body 11 through an air inlet pipe, and when the pressure reaches a preset value, the air inlet valve 31 is closed.
Further, after the closed type pressurized gas dissolving process is finished, the first ore removal valve 115 is opened, and the ore pulp flows out from the first ore removal port 112.
In the invention, various flotation reagents can be added into the stirring barrel 1 through the dosing port in the process of pressurizing and dissolving gas; and simultaneously, water is supplemented into the ore pulp through a water supplementing port so as to adjust the concentration of the ore pulp.
In the invention, the stirring time is 1-20 min.
In the invention, the method also comprises the following steps: and (4) opening a slurry conveying pump 4, and conveying the ore pulp subjected to the pressurization and gas dissolving process to the interface micro-nano bubble controller 2 to regulate and control the hydrophobicity of the mineral interface.
Example 1
Butyl xanthate is used as a collecting agent, lime is used as a pH regulator, water glass is used as an inhibitor, 2# oil is used as a foaming agent, and a direct flotation process is adopted to enrich lead ores. The target mineral in the ore is galena, the lead element grade is 2.80 percent, and the non-target mineral is quartz.
D is 2X 10 -9 m 2 S; rho is 0.40Kg/m 3 (ii) a The delta rho is 999.60Kg/m 3 (ii) a Sigma of 71.98 × 10 -3 N/m；P 2 Is 0.05 Mpa; c s Is 1.11X 10 -2 Kg/m 3 (ii) a The growth time of the micro-nano bubbles (namely the flowing time of ore pulp in the second pipeline) is 4 s; a is 4.26 × 10 -4 ，b＝30，g＝9.8m/s 2 Taking P 1 Step size of 0.1MPa, then P 1 ＝0.1,0.2,0.3,0.4,0.5,0.6,0.7Mpa；C ∞ ＝0.0225,0.0450,0.0675,0.0900,0.1125,0.1350,0.1575Kg/m 3 (ii) a Galena: the initial radius R of the constant contact angle growth of the bubbles is 10.01 multiplied by 10 -6 m；
Quartz: the initial radius R of the constant contact angle growth of the bubbles is 6.99 multiplied by 10 -6 m；
Critical radius R of bubbles on surfaces of galena and quartz under different pressures d Radius R when growth time T is 4s T Surface area S of bubble at time T T The difference Δ S data from the surface area is shown in Table 1:
TABLE 1 data relating to the difference in surface area of different minerals
As can be seen from Table 1, the value of Δ S is maximized at the time of the pressures of 0.6MPa and 0.7MPa in the mixing tank, and the value of pressure of 0.6MPa is selected to reduce the cost; therefore, a closed type pressurized air dissolving method is selected.
In the test, the air inlet valve 31 and the first ore removal valve 115 are closed, the first ore inlet valve 114 and the second ore removal valve 116 are opened to add ore pulp into the barrel body 11, after the ore pulp in the barrel body 11 is added, the first ore inlet valve 114 and the second ore removal valve 116 are closed, the air inlet valve 31 is opened at the same time, air is blown into the barrel body 11, the air pressure is set to be 0.6MPa, the air inlet valve 31 is closed when the pressure reaches a preset value, lime is added through a dosing pump to adjust the pH value to 8, and water glass, ethyl xanthate and No. 2 oil are sequentially added and stirred for 3min, 3min and 2min respectively. After the ore pulp is stirred, the first ore discharging valve 115 is opened, the ore pulp after pressurization and air dissolution flows out from the first ore discharging port 112 and passes through the interface micro-nano bubble controller 2 connected with the ore pulp delivery pump 4, the ore pulp flows out from the interface micro-nano bubble controller 2 and enters a flotation tank of a conventional inflatable flotation machine to start flotation, and the flotation time is 4 min. And (3) finally obtaining galena concentrate and tailings by flotation, respectively drying and weighing, testing the Pb grade of the galena in the concentrate, calculating the recovery rate of the galena concentrate, and comparing the recovery rate with a processing result (as a blank experiment) of a non-pressurized dissolved air pulp mixing device. The experiment carried out by the invention is the same as the blank experiment except that the stirring and size mixing device before flotation is different and the dosage of the added medicament in the invention is less (the stirring and size mixing device used by the blank control is not connected with the air compressor 3, and high-pressure dissolved air cannot be added). The above experiment was repeated, and the grinding fineness was 60%, 70%, 80%, and 90% of-200 mesh (-0.074mm) content, respectively.
Table 2 grade, recovery and chemical dosage of galena flotation concentrate in example 1
Table 2 shows the results of flotation in this example, in which the slurry-mixing treatment was carried out by direct stirring without adding high-pressure dissolved air, and the results of flotation treatment carried out by the flotation slurry-mixing apparatus of the present invention. As can be seen from Table 2, the grade and recovery rate of the flotation concentrate processed by the pulp mixing device are improved. Therefore, after the slurry mixing device disclosed by the invention is used, the grade and the recovery rate of the galena flotation concentrate are greatly improved compared with the treatment without high-pressure dissolved air stirring slurry mixing, and the dosage of the medicament is reduced.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (7)
1. A pressurized dissolved air size mixing method based on interface micro-nano bubbles is characterized by comprising the following steps:
conveying air into the stirring barrel through an air compressor, and performing a pressurizing and air dissolving process on the ore pulp in the stirring barrel;
conveying the ore pulp subjected to the pressurized gas dissolving process to an interface micro-nano bubble controller for mineral interface hydrophobicity regulation;
the pressurized dissolved air size mixing method based on the interface micro-nano bubbles is based on a pressurized dissolved air size mixing device of the interface micro-nano bubbles, and the device comprises: the interface micro-nano bubble control device comprises a stirring barrel, an interface micro-nano bubble controller and an air compressor; an air inlet of the stirring barrel is communicated with an air outlet of the air compressor through an air inlet pipe, an ore outlet of the stirring barrel is communicated with an ore inlet of the interface micro-nano bubble controller through an ore outlet pipe, and the pressurizing and air dissolving process is divided into an open pressurizing and air dissolving process and a closed pressurizing and air dissolving process; when required pressure is 0.1 ~ 0.2Mpa in the agitator, choose open pressurization dissolved gas mode for use, when required pressure is 0.2 ~ 0.7Mpa in the agitator, choose closed pressurization dissolved gas mode for use, agitator internal pressure is confirmed according to following semi-empirical formula:
a1, establishing a semi-empirical formula of the surface area S of the interface micro-nano bubbles in the change process of the bubbles along with time t at different growth stages, wherein the different growth stages comprise an expansion stage of constant contact angle growth and a bubble critical desorption stage:
the surface area of the spherical crown bubble is as follows:
S＝2πRh＝2πR 2 (1+cosθ) (1)
a model based on diffusion theory of R variation with t during the expansion phase of constant contact angle growth is as follows:
the desorption radius R changes along with t in the critical desorption stage of the bubbles based on a diffusion theory model is as follows:
wherein:
in the formula: theta is the bubble contact angle, degree; r is the bubble radius, m; rd is critical desorption radius of air bubbles, m; d is the diffusion coefficient of dissolved gas; rho is the gas density in the mineral surface bubbles, Kg/m 3 (ii) a Delta rho is the density difference between air and liquid, Kg/m 3 (ii) a g is the acceleration of gravity, m/s 2 (ii) a P is the pressure in the mixing tank, N/m 2 (ii) a σ is the bubble-liquid interfacial tension, N/m; c ∞ is the concentration of dissolved gas at the distance where the bubbles are infinite, Kg/m 3 (ii) a Cs is dissolved gas concentration, Kg/m 3 (ii) a τ is dimensionless time; t is the bubble growth time, s; a. b is a constant;
a2, determining the pressure in the stirring barrel by combining the surface area of bubbles at the mineral interface with a Henry formula and the actual situation on site;
the henry formula is: cs ═ K H P 2 ，C∞＝K H P 1 ；
In the formula: KH is henry's constant, the value of which is affected by temperature and solution properties; c ∞ is the concentration of dissolved gas in the bubble infinite distance, Kg/m 3 (ii) a Cs is dissolved gas concentration, Kg/m 3 ；P 1 Is the pressure in the mixing drum; p is 2 The pressure in a second tube body of the interface micro-nano bubble controller;
pressure in the mixing tankP 1 The determination method of (2) is as follows:
a201 from P 1 The range of (A) is as follows: 0.1Mpa to 0.7Mpa, and the range of the obtained C ∞ is as follows: 0.1KH to 0.7KH, and mixing P 1 Dividing a certain step length into a plurality of pressure values in a specified range, calculating a change curve of the bubble radius along with time under different pressure values by combining a formula (2), calculating the slope of the curve through approximate processing, and calculating the critical desorption radius of the bubble by combining a formula (3);
a202, determining the radius when the growth time T of the bubble is T according to the change curve of the radius of the bubble along with time and the critical desorption radius of the bubble: if the radius of the bubbles at the T moment does not exceed the critical desorption radius, the radius of the bubbles is the radius at the T moment, and if the radius exceeds the critical desorption radius, the radius of the bubbles is the critical desorption radius;
a203, calculating the surface area of the mineral interface bubbles by combining the determined bubble radius with the formula (1), wherein the pressure when the difference Delta S between the surface areas of the target mineral and the non-target mineral is maximum is the pressure P in the stirring barrel 1 。
2. The pressurized air dissolving and size mixing method based on interface micro-nano bubbles according to claim 1, wherein the open type pressurized air dissolving process specifically comprises the following steps: under the condition of stirring, opening a first ore inlet valve, a second ore discharging valve and an air inlet valve, closing the first ore discharging valve, enabling ore pulp to enter a barrel body through an ore inlet pipe, and conveying air into the barrel body through an air compressor through an air inlet pipe; the closed type pressurizing and gas dissolving process comprises the following specific steps: under the condition of stirring, closing the air inlet valve and the first ore removal valve, opening the first ore inlet valve and the second ore removal valve, adding ore pulp into the barrel body, closing the first ore inlet valve and the second ore removal valve after the ore pulp in the barrel body is added, simultaneously opening the air inlet valve, conveying air into the barrel body through the air inlet pipe by the air compressor, and closing the air inlet valve when the pressure in the barrel body reaches a preset value.
3. The pressurized dissolved air size mixing method based on interfacial micro-nano bubbles according to claim 1, wherein in the open pressurized dissolved air process, ore pulp directly flows out from the second ore outlet; and after the closed pressurizing and gas dissolving process is finished, opening a first ore removal valve, and enabling ore pulp to flow out of the first ore removal port.
4. The pressurized dissolved air slurry mixing method based on interface micro-nano bubbles as claimed in claim 1, wherein the stirring barrel comprises a barrel body and a stirring mechanism, and the stirring mechanism is arranged through the barrel body; an ore pulp inlet and a first ore outlet are formed in the lower portion of the side face of the barrel body, a second ore outlet is formed in the upper portion of the side face of the barrel body, and the air inlet is formed in the upper portion of the barrel body; a first ore inlet valve is arranged at the ore pulp inlet, a first ore outlet valve is arranged at the first ore outlet, and a second ore outlet valve is arranged at the second ore outlet; the first ore outlet and the second ore outlet are communicated with an ore inlet of the interface micro-nano bubble controller through ore outlet pipes respectively.
5. The pressurized dissolved air slurry mixing method based on interface micro-nano bubbles as claimed in claim 1, wherein an air inlet valve is arranged between the mixing tank and an air inlet pipe of the air compressor, and a slurry conveying pump is further arranged on an ore outlet pipe between an ore outlet of the mixing tank and an ore inlet of the interface micro-nano bubble controller.
6. The pressurized dissolved air slurry mixing method based on the interface micro-nano bubbles according to claim 1, wherein the interface micro-nano bubble controller comprises a first pipe body, a second pipe body and a third pipe body; the feeding end of the first pipe body is communicated with the ore outlet of the stirring barrel through a pipeline, the discharging end of the first pipe body is communicated with the second pipe body, and the inner diameter of the second pipe body is smaller than that of the first pipe body; the feed end of the third pipe body is communicated with the discharge end of the second pipe body, and the inner diameter of the third pipe body is larger than that of the second pipe body.
7. The pressurized dissolved air slurry mixing method based on the interfacial micro-nano bubbles according to claim 6, wherein the lengths of the first tube body and the third tube body are both 0.1-2 m; the ratio of the inner diameters of the first pipe body and the second pipe body is 1: 0.25-0.6, and the inner diameter of the second pipe body is 0.01-0.3 m; the flow rate of ore pulp in the second pipe body is 5-20 m/s, the length is 5-30 m, the pressure in the pipe is 4 Kpa-101 Kpa, and the size of generated interface micro-nano bubbles is 0.1-500 mu m.
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| CN101757987A (en) * | 2010-01-12 | 2010-06-30 | 中南大学 | Flotation column |
| CN206454796U (en) * | 2017-01-09 | 2017-09-01 | 中国矿业大学(北京) | A kind of laboratory coal slime pressure dissolved air floatation device |
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| GB201208773D0 (en) * | 2012-05-18 | 2012-07-04 | Enpure Ltd | Dissolved gas flotation apparatus |
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| CN101757987A (en) * | 2010-01-12 | 2010-06-30 | 中南大学 | Flotation column |
| CN206454796U (en) * | 2017-01-09 | 2017-09-01 | 中国矿业大学(北京) | A kind of laboratory coal slime pressure dissolved air floatation device |
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