A method for treating arsenic-containing waste acid by calcium carbonate and calcium hydroxide method

Abstract

The invention discloses a method for treating arsenic-containing waste acid by a calcium carbonate plus calcium hydroxide method, comprising the following steps: S1: oxidation reaction; S2: neutralization reaction; S3: valuable metal reaction; S4: arsenic removal and fluorine removal reaction, including S41: adding an appropriate amount of calcium hydroxide to a reactor tank three, performing solid-liquid separation after the reaction is completed, harmlessly treating the generated calcium arsenate slag, and transporting the separated liquid to a reactor tank four; S42: adding an appropriate amount of calcium hydroxide to a reactor tank four, and using a feeding device to transport the concentrated slurry generated at the bottom of the reactor tank four to the reactor tank three of the first stage for further reaction after the reaction is completed, and the remaining waste liquid in the reactor tank four is discharged for wastewater treatment. By treating the arsenic-containing waste acid by the calcium carbonate + calcium hydroxide method, harmful substances in the waste acid can be removed, and the amount of arsenic slag generated in the whole process is small, and there will be no overflow of toxic gases.

Description

Technical Field

[0001] The invention relates to the technical field of arsenic-containing waste acid treatment, and in particular to a method for treating arsenic-containing waste acid by a calcium carbonate and calcium hydroxide process. Background Art

[0002] Arsenic waste acid is a common copper smelting industrial wastewater, containing a large amount of acidic substances and harmful substances. If these waste acids are directly discharged into the environment, they will cause great harm to the surrounding ecological environment and human health. Therefore, it is necessary to treat the waste acid.

[0003] During the copper smelting process, the flue gas passes through the sulfuric acid plant purification system, and the waste acid produced by the flue gas is washed and pumped into the waste acid treatment system through the mud. There are many harmful elements in the waste acid, mainly acid, arsenic, fluorine, and copper. The composition of each element is shown in the following table. At present, there are many methods for waste acid treatment, including physical methods, chemical methods and biological methods. Among them, chemical methods are widely used in waste acid treatment because of their stable and reliable treatment effects. Traditional treatment methods mainly include lime-iron salt method and sodium hydrosulfide method + lime-iron salt method, but these methods have the following defects:

[0004] 1. The lime-iron salt method directly uses calcium hydroxide, ferrous sulfate and polyferric sulfate produced by lime to flocculate and further react with arsenic in waste acid to produce more insoluble salts such as ferric pyroarsenite, thereby achieving the purpose of removing arsenic from wastewater. The lime-iron salt method has the advantages of fast precipitation, good arsenic removal effect and low raw material processing cost. The disadvantage is that the amount of arsenic slag produced is large and the cost of harmless disposal is high.

[0005] 2. The sodium hydrosulfide method + lime-iron salt treatment process is to add sodium hydrosulfide to the waste acid, and the produced hydrogen sulfide reacts chemically with the acid, arsenic and copper in the waste acid to achieve the purpose of removing arsenic; the sulfide method + lime method treatment process can realize the recovery of valuable metals in the wastewater, and the treatment process is stable, but it also has defects: high treatment cost, easy to cause H2S gas overflow during the treatment process, and there are safety hazards to the environment and workers. Therefore, this application provides a method for treating arsenic-containing waste acid by calcium carbonate plus calcium hydroxide method to meet the needs. Summary of the invention

[0006] The purpose of the present application is to provide a method for treating arsenic-containing waste acid by calcium carbonate plus calcium hydroxide, so as to solve the technical problems of large amount of arsenic slag and easy overflow of toxic gas caused by the above process.

[0007] To achieve the above object, the present application provides the following technical solution: a method for treating arsenic-containing waste acid by calcium carbonate and calcium hydroxide method, characterized in that it comprises the following steps:

[0008] S1: Oxidation reaction, passing high arsenic waste acid into the oxidation tank, and adding an appropriate amount of hydrogen peroxide into the tank, with a hydrogen peroxide content of 28-30%. After the reaction is completed, the liquid is transported to the reaction tank 1;

[0009] S2: neutralization reaction, adding an appropriate amount of calcium carbonate to the reaction tank 1, the pH is adjusted to 1.5-2.0, after the reaction is completed, solid-liquid separation is performed, and the separated liquid is transported to the reaction tank 2;

[0010] S3: Valuable metal reaction, add an appropriate amount of calcium hydroxide to the reaction tank 2, the pH is adjusted to 8.0-8.5, and after the reaction is completed, solid-liquid separation is performed to obtain hydroxide-based slag, and the separated liquid is transported to the reaction tank 3;

[0011] S4: Arsenic and fluorine removal reaction, comprising the following steps;

[0012] S41: In the first stage, an appropriate amount of calcium hydroxide is added to the reaction tank three, and the pH is adjusted to 10.5-11. After the reaction is completed, solid-liquid separation is performed, the generated calcium arsenate slag is harmlessly treated, and the separated liquid is transported to the reaction tank four;

[0013] S42: In the second stage, an appropriate amount of calcium hydroxide is added to the reaction tank four, and the pH is adjusted to 12.2-12.5. After the reaction is completed, the concentrated slurry produced at the bottom of the reaction tank four is transported to the reaction tank three in the first stage for further reaction by using the feeding equipment, and the remaining waste liquid in the reaction tank four is discharged for wastewater treatment.

[0014] Preferably: in step S2, the calcium carbonate content is more than 95% and the mesh size is more than 325; in step S2, the calcium hydroxide content is more than 95% and the mesh size is more than 325.

[0015] Preferably, in step S2, the pH is adjusted to 2.0; in step S3, the pH is adjusted to 8.0; in step S41, the pH is adjusted to 11; in step S42, the pH is adjusted to 12.5.

[0016] A feeding device comprises a heat collection unit, a heat energy conversion storage unit and a feeding unit;

[0017] Heat collection unit: used to collect the heat generated in the reaction tank 1;

[0018] Thermal energy conversion storage unit: used to convert the heat collected by the heat collection unit into gravitational potential energy and store it, and this gravitational potential energy can be used as a power source to drive the feeding unit;

[0019] Feeding unit: used to pump the concentrated slurry at the bottom of reaction tank four to reaction tank three.

[0020] Preferably, the heat energy conversion storage unit comprises a hollow cylinder mounted on a mounting frame, a weight is movably arranged in the inner cavity of the hollow cylinder, and the upper end of the weight is fixedly connected to the lower end of the connecting rod, the upper end of the connecting rod is in contact with the output end of the telescopic rod fixed on the mounting frame, and a limiting unit is installed on the hollow cylinder for limiting the weight at a certain height, and after contacting the limiting unit to limit the weight, the weight can move downward by gravity;

[0021] The heat collection unit comprises a heat collecting ring fixedly sleeved on the outer wall of the reaction tank 1, the inner wall of the heat collecting ring is in contact with the heat-conducting outer wall of the reaction tank 1, an annular liquid storage cavity is arranged in the heat collecting ring, and a low-boiling-point liquid is arranged in the annular liquid storage cavity, the heat collecting ring is connected to the lower end of the telescopic rod located above through a connecting pipe, and the outer walls of the heat collecting ring and the connecting pipe are both provided with a heat-insulating coating;

[0022] The feeding unit includes an L-shaped toothed plate with one end fixed to the upper end of the connecting rod and a rotating shaft rotatably arranged on the mounting frame, the lower end of the L-shaped toothed plate movably passes through the mounting frame, a one-way sprocket is fixedly installed on the rotating shaft, and the one-way sprocket is toothedly engaged with the L-shaped toothed plate, a crankshaft is installed on the rotating shaft, and a connecting rod is installed on the crankshaft, a piston head is fixed at the lower end of the connecting rod, and the piston head is slidably arranged in the inner cavity of the feeding barrel, the feeding barrel is fixedly installed on the mounting frame, and a liquid inlet pipe and a liquid outlet pipe communicating with the inner cavity of the feeding barrel are respectively provided on the feeding barrel, a liquid inlet one-way valve and a liquid outlet one-way valve are respectively provided on the liquid inlet pipe and the liquid outlet pipe, the liquid inlet pipe is connected to the reaction tank four through a liquid extraction pipe, and the liquid outlet pipe is connected to the reaction tank three through a liquid delivery pipe.

[0023] Preferably, the crankshafts are provided in two numbers, one crankshaft is provided in a U shape on the rotating shaft, and the other crankshaft is provided in an inverted U shape on the rotating shaft.

[0024] Preferably, the limiting unit includes two limiting rods that slide left and right and penetrate the hollow cylinder, and the two limiting rods are located at the lower end of the inner cavity of the hollow cylinder and are provided with extrusion slopes. The outer ends of the two limiting rods are connected to the U-shaped plate through limiting springs, and the U-shaped plate is fixed to the outer wall of the hollow cylinder. Pull ropes are fixed to the outer ends of the two limiting rods, and the two pull ropes are respectively along the axis of the corresponding limiting springs and penetrate the U-shaped plate and the mounting frame in sequence and are fixedly connected to the foot plate. A guide wheel is installed on the U-shaped plate, and the pull rope is partially sleeved on the guide wheel.

[0025] Preferably, limiting plates are fixed on both foot posts of the mounting frame, and plug rods are slidably inserted on both limiting plates, and the upper ends of the two plug rods are respectively fixedly connected to the side ends of the corresponding foot plates.

[0026] Preferably, a plurality of buffer springs are fixed in a circumferential manner on the bottom of the inner cavity of the hollow cylinder, and the upper ends of the plurality of buffer springs are fixedly connected to the lower end of the support plate.

[0027] Preferably, a first permanent magnet is arranged at the axis center of the upper end of the support plate, a second permanent magnet is arranged at the axis center of the lower end of the weight, and the second permanent magnet has the same magnetic pole as the first permanent magnet at the opposite end.

[0028] In summary, the technical effects and advantages of the present invention are as follows:

[0029] The invention has a reasonable structure, and can effectively remove harmful substances in the waste acid by treating the arsenic-containing waste acid through the calcium carbonate + calcium hydroxide method, and the amount of arsenic slag generated in the whole process is small, and no toxic gas overflow will occur;

[0030] In the present invention, a feeding device is provided, which utilizes the heat generated in the neutralization reaction and converts it into the gravitational potential energy of a heavy object for storage. When in use, the gravitational potential energy of the heavy object can do work on the thick slurry at the bottom of the reaction tank four, and pump it into the reaction tank three for reaction, thereby rationally utilizing the heat source and avoiding heat waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 is a system block diagram of the present invention;

[0033] Figure 2 This is the relationship between the pH of waste acid and the grade of gypsum;

[0034] Figure 3 is the relationship between pH and the removal rates of arsenic, fluorine and copper;

[0035] Figure 4 It is a schematic diagram of the three-dimensional structure of the feeding device;

[0036] Figure 5 for Figure 4 The partial surface and enlarged structural diagram;

[0037] Figure 6 This is a schematic diagram of the enlarged structure at A in 5;

[0038] Figure 7 for Figure 4 Schematic diagram of the structure of the feeding unit;

[0039] Figure 8 It is a schematic diagram of the installation structure of the liquid extraction pipe and the reaction tank 4;

[0040] Fig. 9 It is a schematic diagram of the installation structure of the liquid delivery pipe and the reaction tank three.

[0041] In the figure: 1. heat collection unit; 2. heat energy conversion storage unit; 21. hollow cylinder; 22. weight; 23. connecting rod; 24. telescopic rod; 25. limit unit; 251. limit rod; 252. extrusion slope; 253. limit spring; 254. U-shaped plate; 255. guide wheel; 256. pull rope; 257. foot plate; 3. feeding unit; 31. L-shaped tooth plate; 32. rotating shaft; 33. one-way sprocket; 34. connecting rod; 35. feeding cylinder; 36. liquid inlet pipe; 37. liquid outlet pipe; 38. crankshaft; 4. mounting frame; 5. connecting pipe; 6. support plate; 7. buffer spring; 8. liquid extraction pipe; 9. liquid delivery pipe; 10. limit plate; 11. plug rod. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Example: Reference Figure 1 The method for treating arsenic-containing waste acid by a calcium carbonate and calcium hydroxide method is characterized by comprising the following steps:

[0044] S1: Oxidation reaction, passing high arsenic waste acid into the oxidation tank, and adding an appropriate amount of hydrogen peroxide into the tank, with a hydrogen peroxide content of 28-30%. After the reaction is completed, the liquid is transported to the reaction tank 1;

[0045] S2: Acid-base reaction, adding an appropriate amount of calcium carbonate to the reaction tank 1, the pH is adjusted to 1.5-2.0, after the reaction is completed, solid-liquid separation is performed, and the separated liquid is transported to the reaction tank 2;

[0046] S3: Valuable metal reaction, add an appropriate amount of calcium hydroxide to the reaction tank 2, the pH is adjusted to 8.0-8.5, and after the reaction is completed, solid-liquid separation is performed to obtain hydroxide-based slag, and the separated liquid is transported to the reaction tank 3;

[0047] S4: Arsenic and fluorine removal reaction, comprising the following steps;

[0048] S41: In the first stage, an appropriate amount of calcium hydroxide is added to the reaction tank 3, and the pH is adjusted to 10.5-11. After the reaction is completed, solid-liquid separation is performed, the generated calcium arsenate slag is harmlessly treated, and the separated liquid is transported to the reaction tank 4;

[0049] S42: In the second stage, an appropriate amount of calcium hydroxide is added to the reaction tank four, and the pH is adjusted to 12.2-12.5. After the reaction is completed, the concentrated slurry produced at the bottom of the reaction tank four is transported to the reaction tank three in the first stage for further reaction by using the feeding equipment, and the remaining waste liquid in the reaction tank four is discharged for wastewater treatment.

[0050] The present invention mainly has the following reaction mechanism

[0051] (1) Oxidation reaction (1-2 hours; industrial hydrogen peroxide content 28-30% (tests show that 28-30% concentration of hydrogen peroxide has the best oxidation effect, which can oxidize 95% of arsenous acid into arsenic acid, and then react with calcium hydroxide to produce more stable calcium arsenate, which has a better arsenic removal effect).

[0052] Arsenous acid and hydrogen peroxide in high-arsenic waste acid react as follows: H3AsO3 + H2O2 → H3AsO4 + H2O.

[0053] (2) Neutralization reaction (1-2 hours; pH 2.0; calcium carbonate content above 95% (can improve the quality of gypsum after neutralization), above 325 mesh (can increase the neutralization reaction time and reaction speed);

[0054] The sulfuric acid in the high-arsenic waste acid reacts with the calcium carbonate emulsion as follows: CaCO3+H2SO4→CaSO4↓+H2O+C02↑.

[0055] The sulfuric acid in the high-arsenic waste acid reacts with the calcium hydroxide emulsion (calcium carbide will also undergo hydrolysis in water or an acidic environment to produce calcium hydroxide, and then produce calcium hydroxide emulsion) as follows: Ca(OH)2+H2SO4→CaSO4↓+2H2O.

[0056] (3) Valuable metal reaction (0.5-1 hour; pH 8.0-8.5; calcium hydroxide content above 95%, above 325 mesh)

[0057] The metal compound in the high-arsenic waste acid: copper sulfate, reacts with 2) calcium hydroxide as follows: Ca(OH)2+CuSO4=Cu(OH)2↓+CaSO4.

[0058] (4) Arsenic removal reaction (arsenic removal and defluorination reaction, 1-3 hours; first stage PH 10.5-11; second stage PH 12.2-12.5)

[0059] During the acid-base reaction, when the concentration of CaSO4 increases, a certain concentration of Ca 2+ , Ca 2+ It reacts with arsenates and arsenites to form precipitates.

[0060] 3Ca(OH)2+2H3ASO3→Ca3(AS03)2↓+6H2O

[0061] 3Ca(OH)2+2H3ASO4→Ca3(AS04)2↓+6H2O

[0062] Since calcium hydroxide is used as an arsenic removal agent, as the arsenic content decreases, the arsenic removal efficiency of calcium hydroxide gradually decreases. When the pH is between 8 and 11, it is the main reaction stage of arsenic and fluorine. The fluorine removal rate in this stage reaches 99.98%, but the arsenic removal rate is 99.5%, which does not meet the treatment requirements. When the arsenic in the solution decreases to 400 mg / L, the same amount of calcium hydroxide cannot continue to react with the low-content arsenic. The arsenic-calcium molar ratio in the solution needs to be increased to 1:4 to reduce the arsenic in the solution to below 10 mg / L. At this time, the pH is 12.5, resulting in excessive consumption of calcium hydroxide, which increases the final amount of arsenic slag and increases the corresponding cost of harmless disposal of arsenic slag. In order to keep calcium hydroxide and arsenic in a saturated reaction state, the low-arsenic slag produced in the pH11-12.5 stage is returned to the pH8-11 stage to allow calcium hydroxide to fully react with high arsenic, ultimately achieving the goal of low slag volume.

[0063] (5) Fluoride removal reaction

[0064] The calcium in the spent acid will react with fluoride to produce calcium fluoride precipitate as its concentration increases.

[0065] Ca(OH)2+H2SiF6→CaSiF6↓+2H2O

[0066] 3Ca(OH)2+H2SiF6→3CaF6↓+SiO2+4H2O

[0067] As a preferred implementation in this embodiment, in step S2, the calcium carbonate content is above 95% and above 325 meshes, and in step S2, the calcium hydroxide content is above 95% and above 325 meshes.

[0068] As a preferred implementation in this embodiment, Figure 2-Figure 3 As shown, in step S2, the pH is adjusted to 2.0; in step S3, the pH is adjusted to 8.0; in step S41, the pH is adjusted to 11; and in step S42, the pH is adjusted to 12.5.

[0069] 1. Effect of calcium carbonate reaction endpoint on gypsum quality

[0070] The reaction between calcium carbonate (CaCO3) and dilute sulfuric acid (H2SO4) produces gypsum (CaSO4·2H2O) while releasing carbon dioxide (CO2) gas. The endpoint of the reaction will have a certain effect on the quality of the gypsum, depending on the molar ratio of the reactants and the reaction conditions. Ideally, if calcium carbonate and sulfuric acid react in a stoichiometric ratio, that is, 1 mole of CaCO3 reacts with 1 mole of H2SO4, then theoretically 1 mole of gypsum can be obtained. In this case, the mass of gypsum is equal to the mass of the reactants. However, in actual situations, there are some factors that affect the reaction endpoint and the quality of gypsum. If the molar ratio of the reactants is different from the theoretical stoichiometric ratio, that is, the reactants are excessive or insufficient, then the endpoint of the reaction will be affected. If the calcium carbonate is excessive relative to the sulfuric acid, then there may be unreacted calcium carbonate remaining, resulting in a gypsum mass lower than the theoretical value. Conversely, if the sulfuric acid is excessive, then there may be unreacted sulfuric acid remaining, which will also affect the quality of the gypsum. The relationship between the pH endpoint of the reaction of calcium carbonate with waste acid and the quality of gypsum calcium sulfate dihydrate can be seen in Figure 2 Experiments have shown that when pH=2, the gypsum quality is best and does not affect subsequent process treatment.

[0071] 2. Effect of pH on copper, fluorine and arsenic content

[0072] Controlling pH plays a vital role in the waste acid treatment process. The pH reaction is divided into four stages: the first stage controls the pH value to 2.0 for the neutralization reaction stage, which can produce qualified gypsum; the second stage controls the pH value to 2.0-8.5 for the gradual reaction stage of metal ions, arsenides and fluorides; the third stage controls the pH value to 8.5-11.0 for the main precipitation reaction stage of arsenides and fluorides; the third stage controls the pH value to 11-12.5 for the final reaction stage of low-content arsenic. In the waste acid treatment process, the relationship between pH value and the removal rate of arsenic, fluoride and copper is shown in Figure 3 As shown in Figure 3, the copper removal curve shows that when the pH reaches 8, the copper removal effect reaches up to 98%, achieving the purpose of recovery; the fluorine curve shows that the defluorination efficiency increases with the increase of pH value, and when the pH value reaches above 10, the defluorination efficiency reaches up to 99.99%; the arsenic removal curve shows that when the pH value reaches above 8, the arsenic removal rate gradually increases with the increase of pH value, and when the pH value reaches 11, the arsenic removal rate reaches 95%, and when the pH reaches 12.5, the arsenic removal efficiency is as high as 99.8%. After the waste acid is treated, the fluorine basically meets the national standard, but the arsenic has not yet reached the national standard, so the filtrate after the waste acid treatment is pumped into the sewage treatment system for further treatment)

[0073] Each step purpose of the present invention is as follows:

[0074] 1): Oxidation reaction, by adding hydrogen peroxide, the trivalent arsenic in the waste acid is oxidized to pentavalent arsenic (pentavalent arsenic is easy to react chemically and produce precipitation).

[0075] 2): Neutralization reaction, converting sulfuric acid in waste acid into gypsum by adding calcium carbonate.

[0076] 3): Copper removal reaction, by adding calcium hydroxide to precipitate copper in the form of copper hydroxide, the purpose of copper removal is achieved;

[0077] 4): Arsenic and fluoride removal reactions: By adding calcium hydroxide and adjusting the pH, arsenic is precipitated in the form of calcium arsenate and fluorine is precipitated in the form of calcium fluoride to achieve the purpose of arsenic and fluoride removal.

[0078] Beneficial effects of the present invention

[0079] (1) By first neutralizing the sulfuric acid in the high-arsenic waste acid with calcium carbonate, qualified gypsum can be produced while reducing the amount of calcium arsenate waste slag (since the waste acid contains two substances, sulfuric acid and arsenic, both of which will react with calcium hydroxide. If calcium hydroxide is used to remove arsenic, part of the calcium hydroxide will react with the acid, thereby increasing the amount of arsenic slag. If calcium carbonate is used to control the pH to 2 first, calcium carbonate will only react with acid and will not react with arsenic. In this way, after acid removal, not only qualified gypsum can be produced, but also the total amount of arsenic slag in the arsenic removal process can be reduced, so that the arsenic slag meets the requirements for harmless disposal);

[0080] (2) By adjusting pH and adding calcium hydroxide, valuable copper recovery can be achieved, thereby increasing the copper recovery rate of copper smelting enterprises;

[0081] (3) The calcium arsenate slag at the pH 11-12.5 stage is returned to the pH 8.0-11.0 stage to continue arsenic removal, so that the excess calcium hydroxide and arsenate can fully react, thereby achieving the advantages of low slag volume and good arsenic removal effect.

[0082] It should be noted that in steps S1-S4, the reaction tank is provided with a stirring system for mixing and stirring to accelerate the reaction, and calcium fluoride precipitate is also separated during the third solid-liquid separation.

[0083] like Figure 4 As shown, a feeding device comprises a heat collection unit 1, a heat energy conversion storage unit 2 and a feeding unit 3;

[0084] Heat collection unit 1: used to collect the heat generated in the reaction tank 1;

[0085] Thermal energy conversion storage unit 2: used to convert the heat collected by the heat collection unit 1 into gravitational potential energy and store it, and this gravitational potential energy can be used as a power source to drive the feeding unit 3;

[0086] Feeding unit 3: used to pump the concentrated slurry at the bottom of reaction tank four to reaction tank three.

[0087] The heat generated by the neutralization reaction in the reaction tank one is collected by the heat collection unit 1 and converted into gravitational potential energy by the heat energy conversion and storage unit 2. The gravitational potential energy is then used to work on the feeding unit 3 to pump the concentrated slurry at the bottom of the reaction tank four to the reaction tank three, so as to reasonably utilize the heat generated in the reaction and avoid heat waste.

[0088] As a preferred implementation in this embodiment, Figure 4-9 As shown, the heat energy conversion storage unit 2 includes a hollow cylinder 21 mounted on the mounting frame 4, a weight 22 is movably arranged in the inner cavity of the hollow cylinder 21, and the upper end of the weight 22 is fixedly connected to the lower end of the connecting rod 23, and the upper end of the connecting rod 23 contacts the output end of the telescopic rod 24 fixed on the mounting frame 4, and a limiting unit 25 is installed on the hollow cylinder 21, which is used to limit the weight 22 at a certain height. After the weight 22 is limited by the contact limiting unit 25, the weight 22 can move downward by gravity;

[0089] The heat collection unit 1 includes a heat collecting ring fixedly sleeved on the outer wall of the reaction tank 1, the inner wall of the heat collecting ring is in contact with the heat-conducting outer wall of the reaction tank 1, an annular liquid storage cavity is provided in the heat collecting ring, and a low-boiling-point liquid is provided in the annular liquid storage cavity, the heat collecting ring is connected to the lower end of the telescopic rod 24 located above through a connecting pipe 5, and the outer walls of the heat collecting ring and the connecting pipe 5 are both provided with a heat-insulating coating;

[0090] The feeding unit 3 includes an L-shaped toothed plate 31 with one end fixed to the upper end of the connecting rod 23 and a rotating shaft 32 rotatably arranged on the mounting frame 4. The lower end of the L-shaped toothed plate 31 movably passes through the mounting frame 4. A one-way sprocket 33 is fixedly installed on the rotating shaft 32, and the one-way sprocket 33 is toothed with the L-shaped toothed plate 31. A crankshaft 38 is installed on the rotating shaft 32, and a connecting rod 34 is installed on the crankshaft 38. A piston head is fixed to the lower end of the connecting rod 34, and the piston head is slidably arranged in the inner cavity of a feeding barrel 35. The feeding barrel 35 is fixedly installed on the mounting frame 4. A liquid inlet pipe 36 and a liquid outlet pipe 37 communicating with the inner cavity of the feeding barrel 35 are respectively provided on the feeding barrel 35. A liquid inlet one-way valve and a liquid outlet one-way valve are respectively provided on the liquid inlet pipe 36 and the liquid outlet pipe 37. The liquid inlet pipe 36 is connected to the reaction tank four through the liquid extraction pipe 8, and the liquid outlet pipe 37 is connected to the reaction tank three through the liquid delivery pipe 9.

[0091] When the neutralization reaction in the reactor tank 1 generates heat, the heat is transferred to the ring body and heats the low-boiling-point liquid in the ring body. The low-boiling-point liquid absorbs heat and vaporizes, and the inner cavity of the ring body generates high pressure. The high-pressure gas enters the inner cavity of the telescopic rod 24 through the connecting pipe 5, and causes the output end of the telescopic rod 24 to drive the weight 22 to move upward, and is finally restricted to a certain height by the limiting unit 25. After the neutralization reaction is completed, the high-pressure gas in the ring body, the connecting pipe 5 and the telescopic rod 24 is liquefied through the heat exchange between the telescopic rod 24 and the external environment, and the internal pressure is reduced, and finally the output end of the telescopic rod 24 is restored to its original position (the time from the end of the neutralization reaction to the end of the reaction in the reactor tank 4 is long enough for the gas to liquefy and When the weight 22 needs to do work, the limit unit 25 can release the limit of the weight 22, so that the weight 22 moves downward by gravity. When the weight 22 moves downward, the cooperation of the L-shaped toothed plate 31 and the one-way sprocket 33 drives the rotating shaft 32 to rotate (when the weight 22 moves upward, the L-shaped toothed plate 31 cannot drive the rotating shaft 24 to rotate through the one-way sprocket 33, and the one-way sprocket 33 does not affect the upward movement of the L-shaped toothed plate 31). The rotation of the rotating shaft 32 will drive the connecting rod 34 to do piston movement, thereby pumping the concentrated liquid at the bottom of the reaction tank four into the reaction tank three, making full use of the heat generated in the reaction, effectively avoiding heat waste and saving resources.

[0092] It should be noted that balls are provided on the outer wall of the weight 22 to reduce the friction between the weight 22 and the inner wall of the hollow cylinder 21 .

[0093] As a preferred implementation in this embodiment, Figure 4 and Figure 7 As shown, two crankshafts 38 are provided, one crankshaft 38 is provided on the rotating shaft 32 in a U shape, and the other crankshaft 38 is provided on the rotating shaft 32 in an inverted U shape.

[0094] Two crankshafts 38 are provided, and correspondingly, matching connecting rods 34, hollow cylinders 35, liquid extraction tubes 8 and liquid delivery tubes 9 are provided. When the rotating shaft 32 rotates, as the two crankshafts 38 move up and down alternately, when one of the delivery tubes 35 extracts liquid from the reaction tank four, the other delivery tube 35 presses the liquid inside it into the reaction tank three. In this alternating manner, in conjunction with the two liquid extraction tubes 8, liquid can be continuously injected into the reaction tank three, which is beneficial to speed up the injection of the reaction tank three. At the same time, the two crankshafts 38 are provided, which can effectively slow down the speed at which the weight 22 falls to the bottom of the hollow cylinder 21, so as to prevent the weight 22 from colliding too violently with the bottom of the hollow cylinder 21 (generating noise and easily causing damage to components).

[0095] It should be noted that the number of crankshafts is 2N (where N can be one, two, three, ...), and N crankshafts 38 are arranged in a U shape, and another N crankshafts 38 are arranged in an inverted U shape.

[0096] As a preferred implementation in this embodiment, Figure 5 and Figure 6 As shown, the limiting unit 25 includes two limiting rods 251 that slide left and right and penetrate the hollow cylinder 21. The two limiting rods 251 are located at the lower end of the inner cavity of the hollow cylinder 21 and are provided with an extrusion slope 252. The outer ends of the two limiting rods 251 are connected to the U-shaped plate 254 through a limiting spring 253. The U-shaped plate 254 is fixed on the outer wall of the hollow cylinder 21. Pull ropes 256 are fixed on the outer ends of the two limiting rods 251. The two pull ropes 256 are respectively along the axis of the corresponding limiting spring 253 and penetrate the U-shaped plate 254 and the mounting frame 4 in sequence and are fixedly connected to the foot plate 257. A guide wheel 255 is installed on the U-shaped plate 254, and the pull rope 256 is partially sleeved on the guide wheel 255.

[0097] When the weight 22 moves upward, the upper end of the weight 22 will be squeezed with the extrusion slope 252 of the limit rod 251, and the weight 22 finally moves to the top of the limit rod 251. As the output end of the telescopic rod 24 descends, the lower end of the weight 22 finally contacts the upper end of the limit rod 251 to form a support. At this time, the limit rod 251 limits the weight 22 at a certain height. When the weight 22 needs to be used to do work, the foot plate 257 can be pressed downward with the foot, and the limit rod 26 can be moved outward relative to the hollow cylinder 31 through the pull rope 256, thereby releasing the support of the limit rod 251 for the weight 22. At this time, the weight 22 moves downward to do work on the feeding unit 3, and the limit unit 25 can automatically limit the weight 22, and the limit release operation is also relatively convenient and quick.

[0098] It should be noted that balls can be provided on the four side ends of the limiting rod 251 to reduce the friction between the hollow cylinder 31 and the weight 22, so that a person can release the limit on the weight 22 by applying a smaller force.

[0099] As a preferred implementation in this embodiment, Figure 5 As shown, the two foot columns of the mounting frame 4 are both fixed with limit plates 10, and the two limit plates 10 are both slidably plugged with plug rods 11, and the upper ends of the two plug rods 11 are respectively fixedly connected to the side ends of the corresponding foot plates 257. The setting of the limit plates 10 and the plug rods 11 is to limit the suspended foot plates 257, which is beneficial to ensure the stability of the feet of the personnel.

[0100] As a preferred implementation in this embodiment, Figure 5 As shown, a plurality of buffer springs 7 are fixed in a circumferential manner at the bottom of the inner cavity of the hollow cylinder 21 , and the upper ends of the plurality of buffer springs 7 are fixedly connected to the lower end of the support plate 6 .

[0101] The buffer spring 7 can be used to buffer the weight 22 to prevent the weight 22 from being damaged due to excessive collision.

[0102] It should be noted that an elastic buffer pad is provided at the upper end of the support plate 6 to provide collision buffering and reduce noise and light intensity.

[0103] As a preferred implementation mode in this embodiment, not shown in the figure, a first permanent magnet is arranged at the axis center of the upper end of the support plate 6, and a second permanent magnet is arranged at the axis center of the lower end of the weight 22, and the second permanent magnet has the same magnetic pole at the opposite end as the first permanent magnet, and the repulsive force generated between the two permanent magnets is large enough, and the weight 22 can be buffered by the generated repulsive force. When the weight 22 is stable, the weight 22 is suspended above the support plate 6, and the two permanent magnets do not contact each other (in the whole process), which can directly avoid the collision between the weight 22 and the support plate 6, thereby avoiding the generation of collision noise. At the same time, when the first permanent magnet at the lower end of the weight 22 is about to collide with the first permanent magnet, the compression of the buffer spring 7 can extend the distance of the repulsive force on the weight 22, and while forming a good deceleration for the weight 22, the possibility of collision between the two permanent magnets is further avoided.

[0104] It should be noted that, in order to reduce the interference of the permanent magnet in the hollow cylinder 21 to the external devices, magnetic isolation coatings are provided on the inner and outer walls of the hollow cylinder 21 to suppress the interference of the magnetic field to the outside world.

[0105] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating arsenic-containing waste acid by calcium carbonate and calcium hydroxide method, characterized in that: The steps include: S1: Oxidation reaction, passing high arsenic waste acid into the oxidation tank, and adding an appropriate amount of hydrogen peroxide into the tank, with a hydrogen peroxide content of 28-30%. After the reaction is completed, the liquid is transported to the reaction tank 1; S2: neutralization reaction, adding an appropriate amount of calcium carbonate to the reaction tank 1, the pH is adjusted to 1.5-2.0, after the reaction is completed, solid-liquid separation is performed, and the separated liquid is transported to the reaction tank 2; S3: Valuable metal reaction, add an appropriate amount of calcium hydroxide to the reaction tank 2, adjust the pH to 8.0-8.5, perform solid-liquid separation after the reaction is completed, and obtain hydroxide-based slag, and the separated liquid is transported to the reaction tank 3; S4: Arsenic and fluorine removal reaction, comprising the following steps; S41: In the first stage, an appropriate amount of calcium hydroxide is added to the reaction tank three, and the pH is adjusted to 10.5-11. After the reaction is completed, solid-liquid separation is performed, the generated calcium arsenate slag is harmlessly treated, and the separated liquid is transported to the reaction tank four; S42: In the second stage, an appropriate amount of calcium hydroxide is added to the reaction tank four, and the pH is adjusted to 12.2-12.

5. After the reaction is completed, the thick slurry produced at the bottom of the reaction tank four is transported to the reaction tank three of the first stage for further reaction by using a feeding device, and the remaining waste liquid in the reaction tank four is discharged for wastewater treatment; The feeding device comprises a heat collection unit (1), a heat energy conversion storage unit (2) and a feeding unit (3); Heat collection unit (1): used to collect heat generated in the reaction tank 1; A heat energy conversion storage unit (2): used to convert the heat collected by the heat collection unit (1) into gravitational potential energy and store it, and this gravitational potential energy can be used as a power source to drive the feeding unit (3); Feeding unit (3): used to pump the concentrated slurry at the bottom of reaction tank 4 to reaction tank 3; The heat energy conversion storage unit (2) comprises a hollow cylinder (21) mounted on a mounting frame (4); a weight (22) is movably arranged in the inner cavity of the hollow cylinder (21); the upper end of the weight (22) is fixedly connected to the lower end of a connecting rod (23); the upper end of the connecting rod (23) contacts the output end of a telescopic rod (24) fixed to the mounting frame (4); a limiting unit (25) is mounted on the hollow cylinder (21) for limiting the position of the weight (22) at a certain height; after the weight (22) contacts the limiting unit (25), the weight (22) can move downward by gravity; The heat collection unit (1) comprises a heat collecting ring fixedly sleeved on the outer wall of the reaction tank, the inner wall of the heat collecting ring being in contact with the heat-conducting outer wall of the reaction tank, an annular liquid storage cavity being provided in the heat collecting ring, and a low-boiling-point liquid being provided in the annular liquid storage cavity, the heat collecting ring being connected to the lower end of the telescopic rod (24) located above via a connecting pipe (5), and the outer walls of the heat collecting ring and the connecting pipe (5) are both provided with a heat-insulating coating; The feeding unit (3) comprises an L-shaped toothed plate (31) with one end fixed to the upper end of the connecting rod (23) and a rotating shaft (32) rotatably arranged on the mounting frame (4); the lower end of the L-shaped toothed plate (31) movably passes through the mounting frame (4); a one-way sprocket (33) is fixedly mounted on the rotating shaft (32), and the one-way sprocket (33) is tooth-engaged with the L-shaped toothed plate (31); a crankshaft (38) is mounted on the rotating shaft (32), and a connecting rod (34) is mounted on the crankshaft (38); the lower end of the connecting rod (34) is A piston head is fixed thereto, and the piston head is slidably arranged in the inner cavity of a feeding barrel (35); the feeding barrel (35) is fixedly mounted on the mounting frame (4); a liquid inlet pipe (36) and a liquid outlet pipe (37) are respectively arranged on the feeding barrel (35) and communicate with the inner cavity of the feeding barrel (35); a liquid inlet check valve and a liquid outlet check valve are respectively arranged on the liquid inlet pipe (36) and the liquid outlet pipe (37); the liquid inlet pipe (36) is connected to the fourth reaction tank via a liquid extraction pipe (8); and the liquid outlet pipe (37) is connected to the third reaction tank via a liquid delivery pipe (9); The crankshafts (38) are provided in two numbers, one crankshaft (38) is provided on the rotating shaft (32) in a U shape, and the other crankshaft (38) is provided on the rotating shaft (32) in an inverted U shape; The limiting unit (25) comprises two limiting rods (251) which penetrate the hollow cylinder (21) in a sliding manner from side to side. The lower parts of the ends of the two limiting rods (251) located in the inner cavity of the hollow cylinder (21) are provided with extrusion inclined surfaces (252). The outer ends of the two limiting rods (251) are connected to a U-shaped plate (254) via limiting springs (253). The U-shaped plate (254) is fixed to the outer wall of the hollow cylinder (21). A pull rope (256) is fixed to the outer ends of the two limiting rods (251). The two pull ropes (256) are respectively connected along the axis of the corresponding limiting springs (253) and penetrate the U-shaped plate (254) and the mounting frame (4) in sequence to be fixedly connected to the foot pedal (257). A guide wheel (255) is installed on the U-shaped plate (254). The pull rope (256) is partially sleeved on the guide wheel (255).

2. The method for treating arsenic-containing waste acid by a calcium carbonate and calcium hydroxide method according to claim 1, characterized in that: In step S2, the pH is adjusted to 2.0; in step S3, the pH is adjusted to 8.0; in step S41, the pH is adjusted to 11; in step S42, the pH is adjusted to 12.

5.

3. The method for treating arsenic-containing waste acid by a calcium carbonate and calcium hydroxide process according to claim 1, characterized in that: Limiting plates (10) are fixed on both foot posts of the mounting frame (4), and plugging rods (11) are slidably plugged into both limiting plates (10), and the upper ends of the two plugging rods (11) are respectively fixedly connected to the side ends of the corresponding foot pedals (257).

4. The method for treating arsenic-containing waste acid by a calcium carbonate and calcium hydroxide process according to claim 1, characterized in that: A plurality of buffer springs (7) are fixed in a circular pattern on the bottom of the inner cavity of the hollow cylinder (21), and the upper ends of the plurality of buffer springs (7) are fixedly connected to the lower end of the support plate (6).

5. The method for treating arsenic-containing waste acid by a calcium carbonate and calcium hydroxide method according to claim 4, characterized in that: A first permanent magnet is arranged at the axis center of the upper end of the support plate (6), and a second permanent magnet is arranged at the axis center of the lower end of the weight (22), and the second permanent magnet has the same magnetic pole as the opposite end of the first permanent magnet.

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