A desulfurization system and method for preparing a saline-alkali soil conditioner from carbide slag desulfurization slurry

Abstract

The application discloses a desulfurization system and method for preparing a saline-alkali soil modifier from calcium carbide slag desulfurization slurry, and relates to the technical field of desulfurization systems. The desulfurization system comprises a desulfurization tower, a slurry circulating pool is arranged at the bottom of the tower body, an acidification air inlet and an acidification air outlet are arranged on an inlet flue, a suspension separation box is arranged, the box body is internally provided with a liquid discharge port at the bottom and an air outlet at the top, the liquid discharge port is connected with the slurry circulating pool through a slurry discharge pump, the air outlet is connected with the acidification air outlet on the inlet flue through an acidification air blower, a stirrer, an acidification air pipe network and a slurry injection pipe network are sequentially arranged in the box body from bottom to top, and a gypsum box is arranged and internally provided with a stirrer; process water and solid gypsum particles in the gypsum box form countercurrent contact. The application can effectively remove high-concentration chlorine ions, heavy metals, silicon oxides, aluminum oxides and other special impurities in the calcium carbide slag desulfurization slurry, and the prepared desulfurization gypsum can be used for saline-alkali soil improvement.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of resources and agriculture, and particularly relates to a desulfurization system and method for preparing a saline-alkali soil conditioner from carbide slag. BACKGROUND

[0002] Carbide slag is an industrial solid waste produced after the hydrolysis of calcium carbide in the production of acetylene, polyvinyl chloride, polyvinyl alcohol, etc. The main component of carbide slag is Ca(OH)2, which is strongly alkaline and has a pH of > 12 when dissolved in water. The preparation of a desulfurization agent from strongly alkaline carbide slag industrial solid waste for wet desulfurization can achieve waste treatment with waste. Due to the strong alkalinity and better solubility of carbide slag, the slurry circulation amount of the wet desulfurization washing process can be reduced, and the investment and operation cost of the wet desulfurization device can be greatly reduced.

[0003] At the same time, the by-product of carbide slag used for wet desulfurization, desulfurization gypsum, can also be resourceized after purification. For example, Chinese patent document CN 110201524 A discloses a semi-dry desulfurization ash resource utilization wet desulfurization device and method. The semi-dry desulfurization ash slurry is introduced into the oxidation concentration mechanism to be oxidized, and the gypsum is layered and precipitated to be discharged. Ash and other fine particle impurities are discharged from the overflow port. Chinese patent document CN 112875740 A discloses a system and method for preparing high-purity gypsum from semi-dry desulfurization ash. The slurry circulation pool is provided with a gas distribution pipe network and a gas distribution hole plate to promote the oxidation of the desulfurization slurry. Ash and other fine particle impurities in the semi-dry desulfurization ash are discharged from the overflow port, and the desulfurization gypsum is concentrated at the bottom of the washing tower and then discharged. However, the above methods can only perform aeration suspension separation and desulfurization gypsum sedimentation discharge on the fine particle ash in the desulfurization slurry. SUMMARY

[0004] The present application intends to expand the carbide slag wet desulfurization gypsum to be used for improving saline-alkali soil. However, it is found in research that the gypsum prepared from the carbide slag desulfurization slurry cannot be directly used for improving saline-alkali soil, and the following technical problems mainly exist:

[0005] (1) The carbide slag contains a high content of chloride ions and heavy metal components. These components will not only pollute the soil when entering the soil with the gypsum, but also further pollute the crops when entering the crops through plant metabolism;

[0006] (2) In the process of calcium carbide hydrolysis, the silicates and aluminum oxides in the calcium carbide ore are also discharged with the calcium carbide slag, and the silicates and aluminum oxides enter the wet desulfurization system and are in ionic state under acidic conditions and in flocculent colloidal state under weak alkaline conditions. The desulfurization gypsum containing silicates and aluminum ions applied to saline-alkali soil will not only hinder the replacement of calcium ions in the gypsum with sodium ions in the soil under weak alkaline conditions, but also further reduce the water and air permeability of the saline-alkali soil, and thus the improvement of the saline-alkali soil cannot be realized.

[0007] Therefore, developing a treatment process for concentrating and purifying the desulfurization gypsum of calcium carbide slag by wet method is the key to realize the preparation of saline-alkali soil improver by desulfurization of calcium carbide slag. The traditional treatment method of desulfurization slurry of calcium carbide slag cannot realize the treatment and purification of special impurities such as high-concentration chlorine ions, heavy metals, silicon oxides and aluminum oxides in the desulfurization slurry of calcium carbide slag.

[0008] In view of the above problems, the present application provides a method for preparing saline-alkali soil improver from desulfurization slurry of calcium carbide slag, which can effectively remove special impurities such as high-concentration chlorine ions, heavy metals, silicon oxides and aluminum oxides in the desulfurization slurry of calcium carbide slag, and the prepared desulfurization gypsum can be used for saline-alkali soil improvement.

[0009] A desulfurization system for preparing saline-alkali soil improver from desulfurization slurry of calcium carbide slag, comprising:

[0010] A desulfurization tower, wherein the inner bottom of the desulfurization tower has a slurry circulation pool, and the sidewall of the desulfurization tower has a flue gas inlet, the flue gas inlet is connected with an inlet flue, and the inlet flue is provided with an acidizing air inlet and an acidizing air outlet;

[0011] A suspension separation tank, wherein the suspension separation tank comprises a tank body, a liquid discharge port located at the bottom of the tank body, a stirrer located in the tank body, an acidizing air pipe network located above the stirrer and above the stirring blades of the stirrer, a slurry injection pipe network located above the acidizing air pipe network, a gas discharge port located at the top of the tank body, and an overflow port located at the sidewall of the tank body;

[0012] A slurry discharge pump, wherein the liquid inlet of the slurry discharge pump is connected with the slurry circulation pool through a pipeline, and the liquid outlet of the slurry discharge pump is connected with the liquid inlet of the slurry injection pipe network through a pipeline;

[0013] An acidizing air fan, wherein the air inlet of the acidizing air fan is connected with the acidizing air inlet of the inlet flue of the desulfurization tower through a pipeline, the air outlet of the acidizing air fan is connected with the air inlet of the acidizing air pipe network through a pipeline, and the gas discharge port at the top of the suspension separation tank is connected with the acidizing air outlet of the inlet flue of the desulfurization tower through a pipeline;

[0014] The gypsum box is internally provided with a stirrer, the bottom of the gypsum box is provided with a gypsum slurry discharge port and a process water inlet, the sidewall is provided with an overflow port, the top is provided with a gypsum slurry inlet, the gypsum slurry inlet is connected with the slurry discharge port at the bottom of the suspension separation box through a thickening pump, the gypsum slurry discharge port is connected with a filter through a gypsum pump, the process water inlet is connected with a process water supplement pipeline, and the process water and the solid gypsum particles form countercurrent contact in the gypsum box.

[0015] The suspension separation box uses the flue gas at the inlet of the desulfurization tower to acidify the desulfurization slurry entering the suspension separation box, so that the silicate and aluminum oxide in the desulfurization slurry are dissolved in water in ionic state. The suspension separation box uses the acidification flue gas to form a bubbling layer above the acidification flue pipe network, so that the impurity particles such as dust, coke in carbide slag, calcium sulfite and calcium hydroxide in the slurry are suspended above the acidification flue pipe network, and the gypsum particles are settled at the bottom of the suspension separation box. The desulfurization slurry is uniformly sprayed into the acidification flue bubble area of the acidification flue pipe network through the slurry injection pipe network, is rapidly neutralized and acidified with the acidification flue bubbles, and the rapid dissolution of the silicate and aluminum oxide and the stratification of the particles are promoted. A stirrer is installed below the acidification flue pipe network for suspending and thickening the gypsum particles settled at the bottom of the suspension separation box. Through the cooperation of the acidification flue pipe network, the slurry injection pipe network and the stirrer in the suspension separation box, the silicate and aluminum oxide in the desulfurization slurry are dissolved in water in ionic state, and the gypsum particles are settled at the bottom of the suspension separation box, so that the separation of the silicate and aluminum oxide in the desulfurization slurry is realized, and at the same time, the impurity particles such as dust, coke in carbide slag, calcium sulfite and calcium hydroxide in the slurry are also suspended above the acidification flue pipe network and discharged from the overflow port with the upper layer of suspension.

[0016] The gypsum particles concentrated liquid with the impurity particles such as silicate, aluminum oxide dust, coke in carbide slag, calcium sulfite and calcium hydroxide is introduced into the gypsum box. The gypsum box is used for cleaning and thickening the gypsum slurry discharged from the bottom of the suspension separation box. The process water enters from the bottom of the gypsum box, the gypsum slurry enters from the top of the gypsum box, the process water and the gypsum particles form countercurrent contact, and through the control of the stirring power, the clear liquid containing chlorine ions is discharged from the overflow port of the gypsum box, and the gypsum particles are settled, suspended and concentrated at the bottom of the gypsum box.

[0017] The suspension separation box and the gypsum box are used in cooperation and can efficiently remove the high-concentration chlorine ions, heavy metals, silicon oxide, aluminum oxide and other special impurities in the carbide slag desulfurization slurry.

[0018] Optionally, the acidification flue pipe network is installed at a position 1 / 3 of the height of the bottom of the suspension separation box and below the slurry liquid surface.

[0019] As a preferred, the slurry injection pipe network comprises a slurry flow pipeline and a plurality of injection heads which are uniformly installed below the flow pipeline and face the acidification flue pipe network.

[0020] As preferred: the outlet spray angle of the spray head is 90-130°, and the spray flow rate is 2.0-8.0 m / s. As preferred: the pH control range in the suspension separation tank is 3.0-5.0.

[0021] As preferred: the desulfurization slurry solid content entering the suspension separation tank is 8%-12%.

[0022] Optionally, the agitator in the gypsum tank is a double-layer agitator.

[0023] As preferred: the double-layer agitator comprises a top shaft and upper and lower layer agitator blades fixed to the top shaft at different heights, and the spacing between the two layers of agitator blades is 0.8-2.0 m.

[0024] As preferred: the height difference between the lower layer agitator blade and the process water inlet is 0.2-0.5 m.

[0025] As preferred: the height difference between the upper layer agitator blade and the process water overflow port is 0.5-1.5 m.

[0026] The arrangement of the agitator in the gypsum tank and the countercurrent contact of the process water are used to improve the dilution effect of the process water on the chlorine ions in the gypsum slurry; the installation height of the agitator blade and the arrangement position of the process water inlet and outlet are in the above preferred matching mode, which is conducive to further improving the dilution effect of the chlorine ions.

[0027] As preferred: the upper and lower layer agitator blades rotate in opposite directions, the upper layer agitator stirring power is 0.2-0.5 kw / m 3 , and the lower layer agitator stirring power is 0.1-0.3 kw / m 3 .

[0028] Optionally, the acidification air inlet is located upstream of the flue gas flow direction of the acidification air exhaust port.

[0029] Optionally, it further comprises a neutralization tank; the liquid inlet of the neutralization tank is connected to the overflow port of the side wall of the suspension separation tank through a pipeline, the bottom liquid outlet of the neutralization tank is connected to the filter press through a neutralization pump, and the clear liquid discharge port of the filter press is connected to the slurry circulation pool of the desulfurization tower.

[0030] Optionally, the neutralization tank is provided with an agitator, a bottom liquid outlet, and a top suspension liquid inlet, an alkali liquid inlet, and a flocculant inlet.

[0031] The neutralization tank is used for neutralizing and flocculating the overflow liquid above the suspension separation tank, the lye enters the neutralization tank from the top, the overflow liquid is adjusted to be weakly alkaline, the silicate ions and aluminum ions in the solution are converted into colloidal silicon oxide and aluminum oxide, and the heavy metal ions are converted into metal oxide precipitates; the flocculating agent enters the neutralization tank from the top, the colloidal substance and particulate matter in the overflow liquid are flocculated, and the stirring effect of the stirrer is strengthened.

[0032] As preferred: the pH of the overflow liquid in the neutralization tank is 8.5-10, the residence time of the overflow liquid is 10-35 min, and the stirring power of the stirrer is 0.9-1.5 kw / m 3 .

[0033] Optionally, the overflow port of the gypsum tank is connected to the carbide slag slurry tank through a pipeline.

[0034] On the basis of solving the problem that the desulfurization gypsum of carbide slag meets the requirement of soil ameliorant for saline-alkali soil, the process water generated in the gypsum purification process is reused, the clear liquid after acidification, neutralization and pressure filtration is sent to the desulfurization slurry circulating tank, and is used for water supplement of the desulfurization tower, so that the slurry operation density of the desulfurization tower is reduced, the water consumption of the desulfurization system and the operation energy consumption of the desulfurization pump are reduced; part of the process water for slurry preparation is used for chlorine removal of the gypsum slurry, and the chlorine-containing wastewater after cleaning is sent to the desulfurization slurry preparation tank, and is used for water supplement of the desulfurization slurry preparation, so that the discharge of the gypsum washing wastewater and the subsequent wastewater treatment cost are effectively reduced.

[0035] Optionally, the acidification air inlet located on the desulfurization tower inlet flue is upstream of the acidification air outlet along the flue gas flow direction.

[0036] The application also provides a desulfurization method for preparing soil ameliorant for saline-alkali soil from carbide slag, which is preferably completed by using the system of the application, and comprises the following steps:

[0037] The desulfurization step of the carbide slag: the desulfurization slurry of the carbide slag is sent to the slurry circulating tank at the bottom of the desulfurization tower, is sent to the spraying layer by the desulfurization pump after atomization, and is reversely contacted with the flue gas entering the desulfurization tower inlet, so that the SO2 in the flue gas and the main component Ca(OH)2 of the carbide slag are subjected to neutralization reaction, the CaSO3 generated after the neutralization reaction is oxidized to generate gypsum particles Ca SO3·2H2O, and at the same time, the dust particles, HCl in the flue gas and the silicate, metal oxide and fine particulate impurities in the carbide slag are also captured into the desulfurization slurry circulating tank in the reverse contact process, the flue gas after washing and purification is dried by the desulfurization tower drying layer, and is discharged from the desulfurization tower flue gas outlet;

[0038] The desulfurization slurry acidification step: the desulfurization slurry which is washed and oxidized in the desulfurization tower circulating slurry pool is pumped by the slurry discharge pump to the slurry injection pipe network in the suspension separation tank, and is sprayed downward in the suspension separation tank at a flow rate of 2.0-8.0 m / s and a spray angle of 90-130° through the spray head of the slurry injection pipe network; at the same time, the acidification fan sends part of the desulfurization tower inlet flue gas to the acidification air pipe network located 0.6-2.0 m below the slurry injection pipe network, and bubbles downward through the gas distribution holes in the acidification air pipe network, and forms a bubbling layer above the acidification air pipe network under the action of the gas bubble buoyancy; the rising acidification flue gas bubbles contact the downwardly sprayed desulfurization slurry to complete the acidification, and the slurry pH value in the suspension separation tank is controlled to be 3.0-5.0 by adjusting the acidification air volume and the desulfurization slurry discharge flow rate.

[0039] The silicon oxide, aluminum oxide and metal oxide in the desulfurization slurry under the acidic condition are converted into ion state and dissolved in water, the low-density fine particles are suspended above the acidification air pipe network under the disturbance of the bubbles, and the high-density large gypsum particles are settled to the bottom of the suspension separation tank under the action of gravity; the acidification air which is completed the acidification treatment is sent to the desulfurization tower inlet flue through the pipe from the exhaust port at the top of the suspension separation tank; under the stirring action of the stirrer at the bottom of the suspension separation tank, the gypsum slurry entering the bottom of the suspension separation tank is in a flowing suspension state, the stirring power in the region below the acidification air pipe network is adjusted to be 0.1-0.5 kw / m 3 , and the solid content of the gypsum slurry at the bottom of the suspension separation tank is controlled to be 40%-55%; the acidic slurry containing ion state silicon ions, metal ions, chloride ions and fine particles in the suspension separation tank is discharged from the overflow port of the side wall of the suspension separation tank;

[0040] Gypsum cleaning and removal of dissolved chloride ions: the gypsum slurry suspended in the bottom of the suspension separation tank is sent to the gypsum tank through the thickening pump, the process water enters the gypsum tank from the bottom of the gypsum tank, and the gypsum particles move downward in the gypsum tank under the action of gravity, and the process water flows upward, so that the process water further washes the gypsum and removes the chloride ions in the gypsum slurry; the gypsum slurry which is cleaned, thickened and dechlorinated is sent to the dehydration belt filter for dehydration, and then is used for saline-alkali land improvement; the process water which is cleaned is sent to the calcium carbide slag slurry preparation pool through the pipe from the overflow port of the side wall of the gypsum tank to provide water for the calcium carbide slag slurry preparation.

[0041] Optionally, it further includes an amphoteric substance and heavy metal ion precipitation separation step, and the acidic slurry containing ion state silicon ions, metal ions, chloride ions and fine particles discharged from the overflow port of the suspension separation tank is resourceized.

[0042] Specifically: the acid slurry containing ionic silicate ions, metal ions, chloride ions and fine particles in the upper layer of the suspension separation tank is sent to the neutralization tank through the overflow port of the side wall of the suspension separation tank via a pipeline, the strong alkaline carbide slag slurry is introduced into the neutralization tank through the alkali liquid inlet at the top of the neutralization tank, the pH of the overflow liquid in the neutralization tank is controlled to be 8.5-10 by adjusting the supply amount of the carbide slag slurry, the silicate ions and aluminum ions in the solution are converted into colloidal silicon oxide and aluminum oxide, and the heavy metal ions are converted into metal oxide precipitates; the polyacrylamide flocculant is introduced into the neutralization tank through the flocculant inlet at the top of the neutralization tank to flocculate the colloidal substances and particulate matters in the overflow liquid; and the neutralized and flocculated neutralization liquid is sent to a filter press for pressure filtration by a neutralization pump, and the filtrate is returned to the slurry circulating pool in the desulfurization tower.

[0043] As preferred, the stirring power of the agitator in the neutralization tank is controlled to be 0.9-1.5 kw / m 3 , and the residence time of the overflow liquid is 10-35 min.

[0044] To further improve the cleaning and purification effect of the gypsum, optionally, in the step of removing the dissolved chloride ions, a double-layer agitator is arranged in the gypsum tank, the upper and lower agitator blades rotate in opposite directions, and the stirring power of the upper agitator is controlled to be 0.2-0.5 kw / m 3 , and the stirring power of the lower agitator is controlled to be 0.1-0.3 kw / m 3 .

[0045] Optionally, in the step of removing the dissolved chloride ions, the solid content of the gypsum slurry at the bottom of the gypsum tank is controlled to be 50%-65%, and the volume ratio of the process water to the slurry entering the gypsum tank is 10:1-20:1.

[0046] Optionally, in the step of removing the dissolved chloride ions, the solid content of the gypsum slurry at the bottom of the gypsum tank is controlled to be 50%-65%, and the volume ratio of the process water to the slurry entering the gypsum tank is 10:1-20:1.

[0047] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0048] (1) The present application provides a solution for preparing a saline-alkali soil conditioner from carbide slag desulfurization gypsum: by acidizing, neutralizing and pressure filtering the carbide slag desulfurization slurry, the impurities such as silicon oxide, metal oxide, coke and smoke dust in the gypsum slurry are removed; by adopting a double-layer stirring and convection washing process, the gypsum particles are efficiently cleaned and dechlorinated; by adopting step-by-step concentration, the purity of the gypsum is improved, and high-purity gypsum is prepared for saline-alkali soil improvement, thereby effectively solving the problems of poor water and air permeability caused by amphoteric substances such as silicon oxide and aluminum oxide, and secondary pollution caused by chloride ions and heavy metal ions in the process of improving saline-alkali soil with carbide slag desulfurization gypsum.

[0049] (2) The application provides a solution for further reducing the energy consumption of the calcium carbide slag wet desulfurization system, which sends the clear liquid after acidification, neutralization and filter pressing to a desulfurization slurry circulating pool, uses it for water supplement of the desulfurization tower, reduces the slurry operation density of the desulfurization tower, reduces the water consumption of the desulfurization system and the energy consumption of the desulfurization pump operation; part of the process water for slurry preparation is used for washing and removing chlorine from the gypsum slurry, and the chlorine-containing wastewater after washing is sent to the desulfurization slurry preparation pool for water supplement of the desulfurization slurry preparation, which effectively reduces the discharge of gypsum washing wastewater and the subsequent wastewater treatment cost. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 It is a process flow diagram of the application.

[0051] The reference signs shown in the figure are as follows:

[0052] 1-desulfurization tower 2-slurry circulating pool 3-desulfurization pump

[0053] 4-inlet flue 5-acidification air inlet 6-acidification air outlet

[0054] 7-spraying layer 8-drying layer 9-flue gas outlet

[0055] 10-slurry discharge pump 11-suspension separation tank 12-first agitator

[0056] 13-acidification air pipe network 14-slurry injection pipe network 15-acidification air fan

[0057] 16-concentration pump 17-gypsum tank 18-second agitator

[0058] 19-gypsum pump 20-belt filter 21-neutralization tank

[0059] 22-third agitator 23-neutralization pump 24-filter press DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the application will be described clearly and completely below in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0062] As Figure 1As shown, a desulfurization system for preparing saline-alkali soil modifier from carbide slag desulfurization slurry includes a desulfurization tower 1, a slurry discharge pump 10, a suspension separation tank 11, an acidification fan 15, a concentration pump 16, a gypsum tank 17, a gypsum pump 19, a belt filter 20, a neutralization tank 21, a neutralization pump 23 and a filter press 24.

[0063] The desulfurization tower 1 has, from bottom to top, a slurry circulation pool 2, a flue gas inlet, a spraying layer 7, a drying layer 8 and a flue gas outlet 9. The flue gas inlet is connected to an inlet flue 4. The inlet flue 4 is provided with an acidification air inlet 5 and an acidification air outlet 6. The acidification air inlet 5 and the acidification air outlet 6 are preferably designed such that the acidification air inlet is located upstream of the acidification air outlet.

[0064] The suspension separation tank 11 includes a tank body. The tank body is a closed tank body. The tank body is provided with a liquid discharge port at the bottom and an exhaust port at the top. An overflow port is provided on the upper portion of the side wall of the tank body. A first agitator 12 is provided in the lower portion of the tank body. The first agitator can be a top shaft agitator or a side agitator. An acidification air pipe network 13 is provided above the paddle of the first agitator. A slurry injection pipe network 14 is provided above the acidification air pipe network 13.

[0065] The liquid inlet of the slurry discharge pump 10 is connected to the slurry circulation pool 2 in the desulfurization tower 1 through a pipeline. The liquid outlet of the slurry discharge pump 10 is connected to the liquid inlet of the slurry injection pipe network 14 in the suspension separation tank 11 through a pipeline. The slurry discharge pump 10 is a desulfurization slurry discharge pump of the carbide slag desulfurization tower.

[0066] The air inlet of the acidification fan 15 is connected to the acidification air inlet 5 on the inlet flue of the desulfurization tower through a pipeline. The air outlet of the acidification fan 15 is connected to the air inlet of the acidification air pipe network 13 through a pipeline. The exhaust port at the top of the suspension separation tank 11 is connected to the acidification air outlet 6 on the inlet flue of the desulfurization tower through a pipeline. The acidification fan 15 is a fan of a conventional flue gas desulfurization system.

[0067] The gypsum tank 17 can also be a closed tank body. A second agitator 18 is provided in the tank body. The tank body is provided with a gypsum slurry discharge port and a process water liquid inlet port at the bottom. The gypsum slurry discharge port and the process water liquid inlet port are staggered. An overflow port is provided on the side wall of the tank body. A gypsum slurry liquid inlet port is provided at the top of the tank body. The gypsum slurry liquid inlet port is connected to the liquid outlet of the suspension separation tank 11 through the concentration pump 16. The gypsum slurry discharge port is connected to the belt filter 20 through the gypsum pump 19. The process water liquid inlet port is connected to a process water supply pipeline. The process water and the solid gypsum particles in the gypsum tank form countercurrent contact. The slurry is fed into the tank body from the top and discharged from the bottom. The process water is fed into the tank body from the bottom and discharged near the top.

[0068] As a preferred combination of acidizing air pipe network, slurry injection pipe network and slurry injection pipe network injection angle, the acidizing air pipe network 13 is installed at a distance of 1 / 3 height of the tank body of the suspension separation tank 11 and below the slurry liquid surface, the slurry injection pipe network 14 is located above the acidizing air pipe network 13 at a height of 0.6-2.0m, the slurry injection pipe network 14 includes a slurry flow pipe and a plurality of injection heads installed uniformly below the flow pipe and towards the acidizing air pipe network, the outlet injection angle of the injection head is 90-130°, and the injection flow rate is 2.0-8.0m / s. Through the introduction of acid flue gas and the cooperation of the above preferred mode, the pH value in the suspension separation tank is controlled in the range of 3.0-5.0.

[0069] The gypsum tank 17 is used as a washing container for chloride ions, the second agitator 18 in the gypsum tank 17 is a double-layer agitator, which includes a top shaft and upper and lower layer agitating blades fixed to the top shaft at different heights, the spacing between the two layers of agitating blades is 0.8-2.0m, the height difference between the lower layer agitating blades and the process water inlet is 0.2-0.5m, and the height difference between the upper layer agitating blades and the process water overflow outlet is 0.5-1.5m. The setting of the second agitator in the gypsum tank and the countercurrent contact of the process water are used to improve the dilution effect of the process water on the chloride ions in the gypsum slurry; under the above preferred cooperation mode, the installation height of the agitating blades and the setting position of the process water inlet and outlet are beneficial to further improve the dilution effect of the chloride ions.

[0070] As a preferred mode, the upper and lower layer agitator blades rotate in opposite directions, the stirring power of the upper layer agitator is 0.2-0.5kw / m 3 , and the stirring power of the lower layer agitator is 0.1-0.3kw / m 3 .

[0071] The application is based on preparing saline-alkali soil modifier from carbide slag slurry, and further comprehensively treating the upper liquid of the suspension separation tank, and recycling to the desulfurization tower system to solve the problem of reducing the energy consumption of the desulfurization tower. An overflow port is arranged on the side wall of the tank body of the suspension separation tank 11, and the overflow port is connected to the neutralization tank 21 through a pipeline. The neutralization tank 21 is provided with a third stirrer 22, a liquid discharge port at the bottom, and a suspension liquid inlet port, an alkali liquid inlet port and a flocculating agent inlet port at the top. The alkali liquid enters the neutralization tank from the top to adjust the overflow liquid to be weakly alkaline. The silicate ions and aluminum ions in the solution are converted into colloidal silicon oxide and aluminum oxide, and the heavy metal ions are converted into metal oxide precipitates. The flocculating agent enters the neutralization tank from the top to flocculate the colloidal substance and particulate substance in the overflow liquid, and the stirring effect is enhanced by the stirrer. The bottom liquid discharge port of the neutralization tank 21 is connected to the filter press 24 through the neutralization pump 23, and the clear liquid discharge port of the filter press 24 is connected to the slurry circulating pool 2. The third stirrer 22 is a top shaft type stirrer. As a preferred embodiment, the pH of the overflow liquid in the neutralization tank is 8.5-10, the residence time of the overflow liquid is 10-35 min, and the stirring power of the stirrer is 0.9-1.5 kw / m 3 .

[0072] The process water overflow port of the gypsum tank 17 is connected to the carbide slag slurry preparation pool through a pipeline. Part of the process water used for slurry preparation is used for washing and removing chlorine from the gypsum slurry, and the chlorine-containing wastewater after washing is sent to the desulfurization slurry preparation pool for water supplement for desulfurization slurry preparation, which effectively reduces the discharge of gypsum washing wastewater and the cost of subsequent wastewater treatment.

[0073] A specific step for preparing saline-alkali soil modifier from carbide slag desulfurization slurry by the above system is as follows:

[0074] (1) The carbide slag desulfurization slurry is sent to the slurry circulating pool at the bottom of the desulfurization tower, and is sent to the spray layer after atomization by the desulfurization pump, and is reversely contacted with the flue gas entering from the flue gas inlet of the desulfurization tower. SO2 in the flue gas reacts with Ca(OH)2, the main component of carbide slag, to generate CaSO3, which is then oxidized to generate gypsum particles (CaSO3·2H2O). At the same time, dust particles, HCl in the flue gas, silicates, metal oxides and coke in the carbide slag, etc. are also in the process of collision, capture and dissolution, etc. into the desulfurization slurry circulating pool. The washed and purified flue gas is dried by the desulfurization tower flue gas outlet after drying by the drying layer, and the slurry solid content in the desulfurization tower slurry circulating pool is controlled to be 8%-12% by adjusting the process parameters.

[0075] (2) The desulfurization slurry after washing, neutralizing and oxidizing is pumped by a slurry discharge pump to a slurry injection pipe network inlet located at the side wall of the suspension separation tank, and is injected downward in the suspension separation tank at a flow rate of 2.0-8.0 m / s and an injection angle of 90-130° through the injection head; the acidification air blower sends part of the flue gas at the inlet of the desulfurization tower to the acidification air pipe network located 0.6-2.0 m below the slurry injection pipe network, and bubbles downward through a plurality of air distribution holes in the acidification air pipe network, and a bubble layer is formed above the acidification air pipe network under the action of the bubble buoyancy. The rising acidification flue gas bubbles and the downwardly injected desulfurization slurry realize uniform and rapid acidification, and by adjusting the acidification air volume and the desulfurization slurry discharge flow rate, the pH value of the slurry in the suspension separation tank is controlled to be 3.0-5.0, the silicon oxide, aluminum oxide and metal oxide in the desulfurization slurry are converted into ionic state, the low-density fine particles such as dust, coke and calcium sulfite are suspended above the acidification air pipe network under the disturbance of the bubbles, and the high-density large particles of gypsum particles are settled to the bottom of the suspension separation tank under the action of gravity, and the acidification air after acidification treatment is sent to the flue at the inlet of the desulfurization tower through the pipe at the top exhaust port of the suspension separation tank; under the stirring action of the stirrer at the bottom of the suspension separation tank, the gypsum slurry entering the bottom of the suspension separation tank is in a flowing and suspended state, and the stirring power in the area below the acidification air pipe network is adjusted to 0.1-0.5 kw / m 3 , and the solid content of the gypsum slurry at the bottom of the suspension separation tank is controlled to be 40%-55%.

[0076] (3) The acidic slurry containing a large amount of ionic silicate ions, metal ions, chloride ions, dust, coke, calcium sulfite and other impurities is sent to the neutralization tank through the pipe at the overflow port of the side wall of the suspension separation tank, the strong alkaline carbide slag slurry is introduced into the neutralization tank through the alkali inlet at the top of the neutralization tank, the overflow liquid pH in the neutralization tank is controlled to be 8.5-10 by adjusting the carbide slag slurry supply amount, the silicate ions and aluminum ions in the solution are converted into colloidal silicon oxide and aluminum oxide, and the heavy metal ions are converted into metal oxide precipitates; the polyacrylamide flocculant is introduced into the neutralization tank through the flocculant inlet at the top of the neutralization tank to flocculate the colloidal substance and the particulate matter in the overflow liquid; the neutralization and flocculation effect is further improved by controlling the stirring power of the stirrer in the neutralization tank to be 0.9-1.5 kw / m 3 , and the residence time of the overflow liquid is 10-35 min. The neutralized liquid after neutralization and flocculation is sent to the filter press for pressure filtration by the neutralization pump, the filtrate is returned to the desulfurization slurry circulating pool, and the removal of the silicon oxide, metal oxide, coke and chimney in the carbide slag gypsum slurry is realized.

[0077] (4) The gypsum slurry at the bottom of the suspension separation tank is pumped to the top of the gypsum tank by the thickening pump, and the process water enters the gypsum tank from the bottom of the gypsum tank, under the action of gravity, the gypsum particles move downward in the gypsum tank, and the process water flows upward, so as to realize the further cleaning of the process water on the gypsum and remove the chloride ions in the gypsum slurry, in order to further improve the cleaning and purification effect of the gypsum, a double-layer agitator is arranged in the gypsum tank, the upper and lower agitator blades rotate in opposite directions, and the stirring power of the upper agitator is controlled to be 0.2-0.5 kw / m 3 , and the stirring power of the lower agitator is controlled to be 0.1-0.3 kw / m 3 . The process water carrying a large amount of chloride ions is sent to the carbide slag slurry tank through the pipeline from the overflow port of the side wall of the gypsum tank to provide water for the carbide slag slurry. The gypsum slurry after cleaning and thickening and dechlorination is pumped to the belt filter for dehydration, and is used for saline-alkali soil improvement.

[0078] Before the process transformation of the present application: the purity of the desulfurization gypsum is about 91% (dry basis after drying), the water content after dehydration by the belt filter is 13%-15%, and the chloride ion in the desulfurization gypsum is about 3 ‰; after the process transformation of the present application: the dry basis purity of the gypsum can reach more than 97%, the water content after dehydration by the belt filter is reduced to 8%-9%, and the chloride ion in the desulfurization gypsum is less than 5 ten-thousandths; the purified gypsum has uniform particles, good air permeability and easy dehydration, and the energy consumption of the belt filter during the dehydration process is reduced by more than 20%.

[0079] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A desulfurization system for preparing a saline-alkali soil conditioner from carbide slag desulfurization slurry, characterized in that, It comprises: a desulfurization tower, the inner bottom of which is provided with a slurry circulating pool, and the sidewall of which is provided with a flue gas inlet, which is communicated with an inlet flue, and the inlet flue is provided with an acidification air inlet and an acidification air outlet; a suspension separation tank, which comprises a tank body, a liquid outlet at the bottom of the tank body, a stirrer in the tank body, an acidification air pipe network above the stirrer, a slurry injection pipe network above the acidification air pipe network, a gas outlet at the top of the tank body, and an overflow outlet at the sidewall of the tank body; a slurry discharge pump, the inlet of which is communicated with the slurry circulating pool through a pipeline, and the outlet of which is communicated with the inlet of the slurry injection pipe network through a pipeline; an acidification air fan, the inlet of which is communicated with the acidification air inlet of the inlet flue of the desulfurization tower through a pipeline, and the outlet of which is communicated with the inlet of the acidification air pipe network through a pipeline, and the gas outlet at the top of the suspension separation tank is communicated with the acidification air outlet of the inlet flue of the desulfurization tower through a pipeline; a gypsum tank, which is provided with a stirrer, a gypsum slurry discharge outlet and a process water inlet at the bottom, an overflow outlet at the sidewall, and a gypsum slurry inlet at the top, the gypsum slurry inlet is communicated with the liquid outlet at the bottom of the suspension separation tank through a thickening pump, the gypsum slurry discharge outlet is connected with a filter through a gypsum pump, the process water inlet is communicated with a process water supplement pipeline, and the process water in the gypsum tank is in countercurrent contact with the solid gypsum particles.

2. The desulfurization system according to claim 1, characterized by, The acidification air pipe network is installed at a position 1 / 3 of the height of the tank body of the suspension separation tank and below the slurry liquid surface; the slurry injection pipe network is located at a position 0.6-2.0 m above the acidification air pipe network.

3. The desulfurization system according to claim 2, characterized by, The slurry injection pipe network comprises a slurry flow pipeline and a plurality of injection heads which are uniformly installed below the flow pipeline and face the acidification air pipe network; the outlet of the injection head is at an angle of 90-130°, and the injection flow rate is 2.0-8.0 m / s.

4. The desulfurization system of claim 1, wherein The pH value in the suspension separation tank is controlled in the range of 3.0-5.0; the solid content of the desulfurization slurry entering the suspension separation tank is 8%-12%.

5. The desulfurization system of claim 1, wherein The stirrer in the gypsum tank is a double-layer stirrer; the double-layer stirrer comprises a top shaft and upper and lower stirring blades which are fixed to the top shaft at different heights, and the distance between the two layers of stirring blades is 0.8-2.0 m.

6. The desulfurization system according to claim 5, wherein The height difference between the lower stirring blade and the process water inlet is 0.2-0.5 m; and the height difference between the upper stirring blade and the process water overflow outlet is 0.5-1.5 m.

7. The desulfurization system of claim 1, wherein It further comprises a neutralization tank; the inlet of the neutralization tank is communicated with the overflow outlet at the sidewall of the suspension separation tank through a pipeline, the liquid outlet at the bottom of the neutralization tank is connected with a filter press through a neutralization pump, and the clear liquid discharge outlet of the filter press is communicated with the slurry circulating pool of the desulfurization tower.

8. The desulfurization system of claim 1, wherein, The overflow outlet of the gypsum tank is connected with a calcium carbide slag slurry preparation pool through a pipeline; and the acidification air inlet on the inlet flue of the desulfurization tower is located upstream of the acidification air outlet in the flue gas flow direction.

9. A method for desulfurization of calcium carbide slags for the preparation of a soil amendment for saline soils, characterized by, The desulfurization system is used for Calcium carbide slag desulfurization step: the calcium carbide slag desulfurization slurry is sent to the slurry circulating pool at the bottom of the desulfurization tower, and is sent to the spray layer by the desulfurization pump after atomization, and is in counter-current contact with the flue gas entering from the flue gas inlet of the desulfurization tower. SO2 in the flue gas reacts with the main component Ca(OH)2 in the calcium carbide slag to generate CaSO3, which is then oxidized to generate gypsum particles CaSO3·2H2O. At the same time, the dust particles, HCl in the flue gas, and silicates, metal oxides, and fine particles in the calcium carbide slag are also captured into the desulfurization slurry circulating pool during the counter-current contact process. The flue gas after washing and purification is dried by the demisting and drying layer, and is discharged from the flue gas outlet of the desulfurization tower. Desulfurization slurry acidification step: the desulfurization slurry in the desulfurization tower circulating slurry pool is pumped by the slurry discharge pump to the slurry injection pipe network in the suspension separation tank, and is injected downward in the suspension separation tank at a flow rate of 2.0-8.0 m / s and an injection angle of 90-130°. At the same time, the acidification blower sends part of the flue gas at the inlet of the desulfurization tower to the acidification air pipe network located 0.6-2.0 m below the slurry injection pipe network, and bubbles downward through the gas distribution holes in the acidification air pipe network. Under the action of the gas bubble buoyancy, a bubbling layer is formed above the acidification air pipe network. The rising acidification flue gas bubbles contact the downwardly injected desulfurization slurry to complete the acidification. The pH value of the slurry in the suspension separation tank is controlled to be 3.0-5.0 by adjusting the acidification air volume and the desulfurization slurry discharge flow. The silicon oxide, aluminum oxide and metal oxide in the desulfurization slurry under acidic conditions are converted into ionic state and dissolved in water, the low-density fine particles are suspended above the acidification air duct network under the disturbance of air bubbles, and the high-density large particles of gypsum particles are settled to the bottom of the suspension separation tank under the action of gravity; the acidification air that has completed the acidification treatment is sent to the inlet flue of the desulfurization tower through the pipeline from the top exhaust port of the suspension separation tank; under the stirring action of the stirrer at the bottom of the suspension separation tank, the gypsum slurry entering the bottom of the suspension separation tank presents a flowing suspension state, the stirring power of the area below the acidification air duct network is adjusted to 0.1-0.5kw / m 3 , the solid content of the gypsum slurry at the bottom of the suspension separation tank is controlled to be 40%-55%; the acidic slurry containing ionic silicon, metal ions, chloride ions and fine particles in the upper layer of the suspension separation tank is discharged from the overflow port of the side wall of the suspension separation tank; Gypsum cleaning and removing dissolved chloride ions: the gypsum slurry suspended at the bottom of the suspension separation tank is sent to the gypsum tank by the thickening pump. Process water enters the gypsum tank from the bottom of the gypsum tank. Under the action of gravity, the gypsum particles move downward in the gypsum tank, and the process water flows upward, so as to realize further cleaning of the gypsum by the process water and remove chloride ions from the gypsum slurry. The gypsum slurry after cleaning, thickening and removing chloride ions is sent to the dehydration belt filter for dehydration, and is used for saline-alkali soil improvement. The process water after cleaning is sent to the calcium carbide slag slurry preparation pool through the pipeline from the overflow port of the gypsum tank side wall to provide water for the preparation of calcium carbide slag slurry.

10. The desulfurization method according to claim 9, characterized by, Also includes: Amphiphilic substance and heavy metal ion precipitation separation: the acid slurry containing ionic silicate ions, metal ions, chloride ions and fine particles in the upper layer of the suspension separation tank is sent to the neutralization tank through the pipeline from the overflow port of the suspension separation tank side wall. The strong alkaline calcium carbide slag slurry enters the neutralization tank from the alkali inlet at the top of the neutralization tank. The pH value of the overflow liquid in the neutralization tank is controlled to be 8.5-10 by adjusting the calcium carbide slag slurry supply amount, so as to convert the silicate ions and aluminum ions in the solution into colloidal silicon oxide and aluminum oxide, and convert the heavy metal ions into metal oxide precipitates. The polyacrylamide flocculant enters the neutralization tank from the flocculant inlet at the top of the neutralization tank to flocculate the colloidal substances and particles in the overflow liquid. The neutralized and flocculated liquid is sent to the filter press by the neutralization pump for pressure filtration, and the filtrate is returned to the slurry circulating pool in the desulfurization tower.

11. The desulfurization method according to claim 10, characterized by, The stirring power of the agitator in the neutralization tank is controlled at 0.9-1.5 kw / m 3 The residence time of the overflow liquid is 10-35 min.

12. The desulfurization method according to claim 9, characterized by, In the step of washing and removing the dissolved chloride ions from the gypsum, a double-layer agitator is arranged in the gypsum tank, the upper and lower agitator blades rotate in opposite directions, and the stirring power of the upper agitator is controlled to be 0.2-0.5 kw / m 3 , and the stirring power of the lower agitator is controlled to be 0.1-0.3 kw / m 3 .

13. The desulfurization method according to claim 9, characterized by, In the step of removing dissolved chloride ions from the gypsum, the solid content of the gypsum slurry at the bottom of the gypsum tank is controlled to be 50%-65%, and the volume ratio of process water to gypsum slurry entering the gypsum tank is 10:1~20:

1.

14. The desulfurization method according to claim 9, characterized by, In the calcium carbide slag desulfurization step, the solid content of the slurry in the desulfurization tower slurry circulating pool is controlled to be 8%-12%.

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