Method and system for recovering chlorous acid-containing mud

Abstract

The invention provides a method and a system for recovering chlorate-containing acid mud. The method for recovering the chlorate-containing mud comprises the following steps: carrying out solid-liquid separation on the chlorate-containing mud under a first pressure condition to obtain acid liquor and formed mud blocks; filtering the acid liquor to obtain filtrate, and circulating the filtrate back to the acid regeneration waste acid tank; the formed mud blocks are heated, and acid-containing waste gas and mud cakes are obtained; carrying out first cooling treatment on the acid-containing waste gas and then circulating the acid-containing waste gas back to the pickling washing tower; and the mud cake is subjected to second cooling treatment, and iron ore is obtained. According to the recycling method, the chlorine-containing mud cake can be treated in an environment-friendly mode, waste is turned into wealth, specifically, the acid mud can be turned into iron ore to be sold, the iron content grade of the iron ore reaches 55% or above, the whole process is free of pollution, high treatment cost does not need to be paid, high income can be obtained from iron ore selling, and the recycling method is suitable for industrial production. And the requirements of safety and environmental protection are met.

Description

Technical Field

[0001] The present invention relates to the field of sludge treatment, and particularly to a method and system for recovering chloric acid-containing sludge. Background Art

[0002] The pickling raw materials contain elements such as silicon, manganese, and aluminum. After pickling, metals such as iron, silicon, and manganese react with hydrochloric acid and enter the waste acid solution. The waste acid is heated to 85°C - 90°C and flows into the leaching tower for further neutralization. The free hydrochloric acid completely reacts with iron to generate hydrogen and ferrous chloride. Subsequently, after the waste acid is cooled, it flows to the reaction tank, and ammonia water is added to increase the pH value. At the same time, compressed air is introduced to oxidize a small part of divalent iron to trivalent iron. Then, a flocculant is added to the mixing tank, and after the flocculation reaction, large Fe(OH) 3 flocs are formed. Finally, silicon dioxide and some metal hydroxides are wrapped in the Fe(OH) 3 flocs and precipitate in the sedimentation tank. After being subjected to pressure filtration and dehydration treatment, it becomes acid sludge.

[0003] The existing acid sludge treatment process is as follows: the sediment at the lower part of the sedimentation tank → filter press → mud cake → truck with carriage → sintering plant for treatment. The above treatment process mainly has the following defects: (1) The acid sludge has a high water content and a pH of 4 - 5.5. During loading, unloading, and transportation, leakage may occur, resulting in wastewater entering the rainwater system and polluting the environment; (2) In addition, after entering the sintering system, it increases the chlorine load on the process, corrodes the sintering equipment, and the annual transportation cost is relatively high; (3) Moreover, the above treatment process is equivalent to giving the acid sludge to the sintering plant for free treatment without any income. However, with the improvement of environmental protection requirements, due to considerations of chlorine load and corrosion of sintering equipment, the sintering plant is currently also reluctant to treat such acid sludge. In order to environmentally treat the chlorine-containing acid sludge, it currently needs to be transported by a special vehicle to a professional treatment factory, and the treatment cost will further increase.

[0004] Therefore, in view of environmental protection requirements and cost pressure, it is urgent to develop a method for effectively recovering and treating chloric acid-containing sludge to solve the problems that leakage may occur during the loading, unloading, and transportation of chloric acid-containing sludge, resulting in wastewater entering the rainwater system and polluting the environment, as well as corrosion of sintering equipment and high treatment cost during the sintering process. Summary of the Invention

[0005] The main object of the present invention is to provide a method and system for recovering chloric acid-containing sludge to solve the problems of high treatment cost of chloric acid-containing sludge, leakage during loading, unloading, and transportation resulting in environmental pollution, and corrosion of sintering equipment during the sintering process.

[0006] To achieve the above object, the present invention provides a method for recovering chloric acid-containing sludge, including:

[0007] (1) Under the first pressure condition, perform solid-liquid separation on the chloric acid-containing mud to obtain acid liquor and formed mud blocks;

[0008] (2) Filter the acid liquor to obtain a filtrate, and recycle the filtrate back to the acid regeneration waste acid tank; and

[0009] Heat-treat the formed mud blocks to obtain acid-containing waste gas and mud cakes;

[0010] (3) After performing the first cooling treatment on the acid-containing waste gas, recycle it back to the acid washing scrubber; and

[0011] Perform a second cooling treatment on the mud cakes to obtain iron ore;

[0012] Wherein, in step (1), the Cl- content in the chloric acid-containing mud is not less than 10 wt%, and the first pressure is 35 - 40 MPa.

[0013] Further, in step (1), the chloric acid-containing mud further contains ferric oxide and water, the ferric oxide content is not less than 40 wt%, and the water content is 30 - 40 wt%.

[0014] Further, in step (1), the solid-liquid separation is carried out in a briquetting machine.

[0015] Preferably, in step (1), by controlling the first pressure and the conditions of the briquetting machine, the size of the formed mud blocks is (900 - 1000) mm × (900 - 1000) mm × (900 - 1000) mm.

[0016] Further, in step (2), the method further includes: introducing the filtrate into a transition tank, and using an acid pump to recycle the filtrate in the transition tank back to the acid regeneration waste acid tank.

[0017] Preferably, in step (2), the acid concentration in the filtrate is 130 - 180 g / L.

[0018] Further, in step (2), the conditions of the heat treatment at least include: the temperature is 500 - 700 °C, and the time is not less than 5 min.

[0019] Further, in step (3), by controlling the conditions of the first cooling treatment, the acid-containing waste gas is cooled to 70 - 85 °C.

[0020] Further, in step (3), by controlling the conditions of the second cooling treatment, the mud cakes are cooled to below 100 °C.

[0021] Further, in step (3), the iron content grade in the iron ore is not less than 55 wt%.

[0022] The present invention also provides a system for recycling chloric acid-containing sludge, comprising:

[0023] A pressure device, which is connected to a filter press and is used to provide pressure to separate the solid and liquid of the chloric acid-containing sludge from the filter press to obtain acid liquid and formed mud blocks;

[0024] A filtering device, one end of which is connected to the pressure device, the other end of which is connected to an acid regeneration waste acid tank, and the filtering device is used to filter the acid liquid obtained after being processed by the pressure device and recycle the filtered filtrate back to the acid regeneration waste acid tank;

[0025] A heating device, which is used to heat-treat the formed mud blocks obtained after being processed by the pressure device to obtain acid-containing waste gas and mud cakes;

[0026] A cooling device, which includes a first cooling mechanism and a second cooling mechanism. The first cooling mechanism is used to perform a first cooling treatment on the acid-containing waste gas obtained after being processed by the heating device, and the second cooling mechanism is used to perform a second cooling treatment on the mud cakes obtained after being processed by the heating device, and the first cooling mechanism is connected to an acid pickling washing tower.

[0027] Preferably, the pressure device is a briquetting machine.

[0028] Preferably, a transition tank and an acid pump are sequentially arranged between the filtering device and the acid regeneration waste acid tank. The transition tank is used to store the filtrate obtained after being filtered by the filtering device, and the acid pump is used to pump the filtrate in the transition tank into the acid regeneration waste acid tank.

[0029] The beneficial effects of the present invention are as follows:

[0030] The present invention innovatively utilizes the existing equipment of acid pickling and acid regeneration to separate the chloride ions and acid-containing wastewater in the acid sludge by solid-liquid separation under a specific pressure. After being filtered, the acid liquid can return to the existing waste acid tank of acid regeneration for recycling. The flue gas generated after heating the formed mud blocks is cooled by a cooler and then enters the existing acid pickling washing tower for purification, and then can be directly discharged through a chimney. The absorbed acid enters the acid pickling and rinsing section. The recycling method provided by the present invention can environmentally treat the chlorine-containing mud cake and turn waste into treasure.

[0031] The recycling method provided by the present invention can also turn the acid sludge into iron ore for external sale, and the iron content grade of the iron ore reaches more than 55 wt%. The whole process is pollution-free. Not only does it not need to pay high treatment costs, but it can also obtain high profits from selling iron ore. The annual comprehensive benefit is as high as 1.58 million yuan, meeting the requirements of safety and environmental protection.

[0032] Based on the existing pickling and acid regeneration equipment, the recovery system provided by the present invention only needs to be configured with a pressure device, a heating device and a cooling device, which has small investment, is convenient and reliable, can achieve continuous profitability, and reduce the environmental protection load. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0034] Figure 1 It is a schematic process flow diagram of the method for recovering chloric acid sludge provided by the present invention.

[0035] DESCRIPTION OF THE REFERENCE NUMERALS

[0036] 10. Pressure device 20. Filter device 30. Transition tank 40. Acid pump 50. Acid regeneration waste acid tank 60. Heating device 70. Cooling device 701. First cooling mechanism 702. Second cooling mechanism 80. Pickling washing tower 90. Transportation mechanism 101. First fan 102. Second fan

[0037] The realization of the object of the present invention, functional features and advantages will be further described in conjunction with the embodiments with reference to the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0039] It should be noted that all directional indications (such as up, down,...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0040] In addition, the descriptions such as "first" and "second" in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. And the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions appears to be contradictory or unable to be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0041] The present invention provides a method for recycling chloric acid-containing mud, comprising the following steps:

[0042] (1) Under a first pressure condition, subject the chloric acid-containing mud to solid-liquid separation to obtain an acid solution and a formed mud cake;

[0043] (2) Filter the acid solution to obtain a filtrate, and recycle the filtrate back to the acid regeneration waste acid tank; and

[0044] Heat-treat the formed mud cake to obtain an acid-containing waste gas and a mud cake;

[0045] (3) After subjecting the acid-containing waste gas to a first cooling treatment, recycle it back to the pickling scrubbing tower; and

[0046] Subject the mud cake to a second cooling treatment to obtain iron ore;

[0047] Wherein, in step (1), the content of Cl in the chloric acid-containing mud - is not less than 10 wt%, and the first pressure is 35 - 40 MPa.

[0048] The method for recycling chloric acid-containing mud provided by the present invention can environmentally treat the chlorine-containing mud cake and turn waste into treasure; on the one hand, the method of the present invention can recycle the chloride ions in the acid mud for the acid regeneration process and the pickling and rinsing section, avoiding the problems of environmental pollution caused by leakage during transportation or equipment corrosion due to sintering in the prior art. On the other hand, the method of the present invention can also purify the iron in the acid mud and turn it into iron ore for external sale. In summary, the whole process of the method of the present invention is pollution-free, not only does not need to pay high treatment costs, but also can obtain high profits from selling iron ore, meeting the requirements of safety and environmental protection.

[0049] It should be noted that the method of the present invention is very suitable for recycling and treating the chloric acid-containing mud generated by the pickling and desilication process. The inventor has found through research that after the chloric acid-containing mud with a specific Cl content generated by the pickling and desilication process is recycled and treated by the method of the present invention, the Cl content can be reduced to less than 1 wt%. - content of the chloric acid-containing mud generated by the pickling and desilication process is recycled and treated by the method of the present invention, the Cl - content can be reduced to less than 1 wt%.

[0050] Furthermore, in step (1), the chloric acid-containing mud further contains ferric oxide and water, and the content of ferric oxide is not less than 40 wt%, and the water content is 30 - 40 wt%.

[0051] The chloric acid-containing mud itself is a kind of resource, and should be utilized through appropriate means in accordance with the principles of "reduction, resource utilization and harmlessness". In particular, the content of ferric oxide in the chloric acid-containing mud generated by the pickling and desilication process is as high as more than 40 wt%, and there is a serious problem of acid corrosion after it is mixed with water, and it needs to be treated harmlessly.

[0052] It should be noted that the chloric acid sludge to be recycled and treated in the present invention also contains a certain amount of metals and their oxides, and its main components have a great corresponding relationship with the product structure of the pickled steel grade. If the product structure changes, the corresponding elements in the acid sludge will also change accordingly. Exemplarily, the chloric acid sludge also contains aluminum trioxide, calcium oxide, titanium dioxide, vanadium pentoxide, zinc oxide, manganese oxide, silicon dioxide and copper oxide. Among them, based on the total mass of the chloric acid sludge, the content of aluminum trioxide is 0.4 - 0.6 wt%, the content of calcium oxide is 0.9 - 1.1 wt%, the content of titanium dioxide is 0.02 - 0.05 wt%, the content of vanadium pentoxide is 0.09 - 0.12 wt%, the content of zinc oxide is 0.004 - 0.006 wt%, the content of manganese oxide is 1.2 - 1.5 wt%, the content of silicon dioxide is 6.0 - 9.0 wt%, and the content of copper oxide is 0.04 - 0.06 wt%.

[0053] If the pressure is too high, it will cause embrittlement during the subsequent sintering process, resulting in the failure of the mud block to form; if the pressure is too low, the extrusion effect is not good, the recycled acid-containing wastewater is insufficient, and some chlorides will volatilize during subsequent sintering, causing corrosion to the equipment. The inventors found that by compressing the chloric acid sludge generated by the pickling and desilication process within a pressure range of 35 - 40 MPa, the acid-containing wastewater in the chloric acid sludge can be extruded as much as possible, significantly reducing the Cl - content.

[0054] In some specific embodiments, in step (1), the solid-liquid separation is carried out in a briquetting machine. It should be noted that the present invention method has no special requirements for the model and type of the briquetting machine, and a briquetting machine known to those skilled in the art can be used, as long as it can provide a pressure of 35 - 40 MPa. Exemplarily, the method of the present invention can use a briquetting machine driven by hydraulic pressure.

[0055] In some specific embodiments, in step (1), by controlling the first pressure and the conditions of the briquetting machine, the size of the formed mud block is made to be (900 - 1000) mm × (900 - 1000) mm × (900 - 1000) mm.

[0056] In some specific embodiments, in step (2), the method further includes: introducing the filtrate into a transition tank, and using an acid pump to circulate the filtrate in the transition tank back to the acid regeneration waste acid tank.

[0057] Preferably, in step (2), the acid concentration in the filtrate is 130 - 180 g / L. The inventors found that by successively compressing and filtering the chloric acid sludge, the acid solution therein is enriched and extruded from the formed mud cake, and can be recycled back to the existing waste acid tank for reuse.

[0058] Preferably, in step (2), the conditions of the heat treatment at least include: the temperature is 500 - 700 °C, and the time is not less than 5 min. If the temperature is too high, it will cause overburning of the mud cake, increase brittleness, and cause partial melting of some metals, damaging the integrity of the mud cake. At the same time, it will also cause waste of energy and subsequent cooling power. If the temperature is too low, it is not sufficient to decompose and discharge the residual chlorides. The inventors found that by adopting the specific implementation manner in this preferred case, the Cl - content in the treated chloric acid sludge can be significantly reduced.

[0059] It should be noted that the present invention has no special requirements for the specific manner of the heat treatment, and heating methods known to those skilled in the art can be adopted, as long as the temperature can be controlled within the range of 500 - 700 °C. Exemplarily, heating treatment is carried out by means of gas, natural gas, etc. Further, the time of the heat treatment in the method of the present invention refers to the average residence time of the formed mud cake in the heating device.

[0060] Further, in step (3), by controlling the conditions of the first cooling treatment, the acid-containing waste gas is cooled to 70 - 85 °C.

[0061] In some specific embodiments, in step (3), the method further includes: the acid-containing waste gas is first subjected to the first cooling treatment by suction with a first fan, then enters an existing pickling scrubbing tower for purification, and then is discharged to the atmosphere by suction with a second fan.

[0062] It should be noted that the present invention method has no special restrictions on the types and process parameters of the first fan and the second fan, and fan types and process parameters known to those skilled in the art can be adopted, as long as the acid-containing waste gas or the purified gas can be extracted.

[0063] After the treatment by the method of the present invention, the gas purified by the pickling scrubbing tower can be directly discharged through the chimney without polluting the environment. At the same time, the acid absorbed by the pickling scrubbing tower can be recovered and enter the pickling and rinsing section.

[0064] Further, in step (3), by controlling the conditions of the second cooling treatment, the mud cake is cooled to below 100 °C.

[0065] It should be noted that the present invention has no special requirements for the method and duration of the first cooling treatment. Any cooling method known to those skilled in the art can be used, as long as the acid-containing waste gas and the mud cake can be cooled to the specified requirements. Exemplarily, the methods of the first cooling treatment and the second cooling treatment are each independently selected from at least one of circulating cooling water and air cooling.

[0066] In some specific embodiments, the first cooling treatment uses circulating cooling water, and the second cooling treatment uses air cooling.

[0067] Further, in step (3), the iron content grade in the iron ore is not less than 55 wt%.

[0068] It should be noted that after the treatment of the method of the present invention, based on the total mass of the iron ore, the contents of other main components in the iron ore are as follows: the content of aluminum trioxide is 0.9 - 1.1 wt%, the content of calcium oxide is 1.6 - 2.0 wt%, the content of titanium dioxide is 0.15 - 0.25 wt%, the content of vanadium pentoxide is 0.15 - 0.2 wt%, the content of zinc oxide is 0.009 - 0.011 wt%, the content of manganese oxide is 2.0 - 3.0 wt%, the content of silicon dioxide is 10.0 - 17.0 wt%, the content of copper oxide is 0.08 - 0.12 wt%, the content of Cl - is not more than 1 wt%, and the content of water is 0.3 - 0.6 wt%.

[0069] The method of the present invention heats the formed mud block to re-dry the mud block. On the one hand, it ensures that the iron chlorides and hydroxides in the mud block are decomposed at high temperature and converted into iron oxides. The acid-containing waste gas generated during the heating treatment enters the existing pickling acid mist scrubber for reuse after cooling treatment; on the other hand, through high-temperature reaction during the heating of the mud block, the iron content grade in the iron ore can be improved.

[0070] As Figure 1 shown, the present invention also provides a system for recovering acid-containing mud, including:

[0071] A pressure device 10, which is connected to a filter press and is used to provide pressure to separate the acid-containing mud from the filter press into a liquid phase and a formed mud block;

[0072] Filter device 20, one end of the filter device 20 is communicated with the pressure device, the other end of the filter device 20 is connected to the acid regeneration waste acid tank 50, and the filter device 20 is used to filter the acid solution obtained by the treatment of the pressure device 10 and recycle the filtered filtrate back to the acid regeneration waste acid tank 50;

[0073] Heating device 60, the heating device 60 is used to heat the formed mud block obtained by the treatment of the pressure device 10 to obtain acid-containing waste gas and mud cake;

[0074] Cooling device 70, the cooling device 70 includes a first cooling mechanism 701 and a second cooling mechanism 702. The first cooling mechanism 701 is used to perform a first cooling treatment on the acid-containing waste gas obtained by the treatment of the heating device 60, and the second cooling mechanism 702 is used to perform a second cooling treatment on the mud cake obtained by the treatment of the heating device 60, and the first cooling mechanism 701 is connected to the pickling washing tower 80.

[0075] Based on existing pickling and acid regeneration equipment such as acid regeneration waste acid tanks and pickling washing towers, the recovery system provided by the present invention only needs to configure a small number of devices such as a pressure device, a heating device, and a cooling device, with small investment, convenience and reliability, and can achieve continuous profitability and reduce the environmental protection load.

[0076] In some specific embodiments, the pressure device 10 is a briquetting machine.

[0077] In some other specific embodiments, the filter device 20 is a filter, and the heating device 60 is a heating furnace.

[0078] In some specific embodiments, the precision of the filter is 800 - 1200 μm.

[0079] In some specific embodiments, a transition tank 30 and an acid pump 40 are sequentially arranged between the filter device 20 and the acid regeneration waste acid tank 50. The transition tank 30 is used to store the filtrate obtained by filtering through the filter device 20, and the acid pump 40 is used to pump the filtrate in the transition tank 30 into the acid regeneration waste acid tank 50.

[0080] In some specific embodiments, the volume of the transition tank 30 is 10m 3 .

[0081] In some other specific embodiments, the range of the acid pump 40 is 30m.

[0082] According to a particularly preferred specific embodiment, the system for recycling chloric acid-containing mud further includes a transportation mechanism 90 for sequentially transporting the formed mud blocks past a heating device 60 and a second cooling mechanism 702. The system provided by the present invention uses the transportation mechanism to uniformly heat and cool a large number of formed mud blocks in sequence, which is convenient for subsequent stacking and selling, and greatly saves the labor handling cost.

[0083] Preferably, the transportation mechanism 90 is a chain conveyor.

[0084] According to a particularly preferred specific embodiment, a first blower 101 is further provided between the heating device 60 and the second cooling mechanism 702, and a second blower 102 is also connected to the pickling scrubber 80. The first blower 101 is used to introduce the acid-containing waste gas generated in the heating device 60 into the second cooling mechanism 702, and the second blower 102 is used to discharge the waste gas remaining after the pickling scrubber 80 absorbs it into the atmosphere.

[0085] The following combines Figure 1 Provide a process flow of a preferred specific embodiment of the method for recycling chloric acid-containing mud of the present invention:

[0086] (1) The chloric acid-containing mud in the filter press falls from the top of the briquetting machine into the briquetting machine by its own gravity, and the chloric acid-containing mud is extruded by the briquetting machine under a first pressure to obtain acid liquid and formed mud blocks;

[0087] (2) The acid liquid in the chloric acid-containing mud passes through an overflow valve at the lower water collecting tray of the briquetting machine, and the particles carried in the acid liquid are filtered through a filter to obtain a filtrate. The filtrate is introduced into a transition tank. When the liquid level of the transition tank reaches 90%, an acid pump is automatically started to pump the acid liquid into the existing acid regeneration waste acid tank; and

[0088] The formed mud blocks are transported to the inlet of the chain conveyor. As the chain conveyor runs, they are gradually heated in a heating furnace to obtain acid-containing waste gas and mud cakes;

[0089] (3) The acid-containing waste gas generated in the heating furnace is introduced into a first cooling mechanism by a first blower for cooling, then enters an existing pickling acid mist scrubber for purification and reuse, and the remaining waste gas is introduced into a chimney and discharged through a second blower; and

[0090] The mud cakes after high-temperature reaction during the heating treatment are cooled by a second cooling mechanism and stacked to obtain iron ore;

[0091] Among them, the Cl - content in the chloric acid-containing mud is not less than 10 wt%, and the first pressure is 35 - 40 MPa.

[0092] The present invention will be described in detail below with reference to examples. In the following examples, various raw materials and instruments used are commercially available unless otherwise specified.

[0093] It should be noted that the chloric acid sludge in the following examples is all from the waste acid after pickling in Valin ArcelorMittal Automotive Steel Co., Ltd., and is the acid sludge generated through the pickling desilication process.

[0094] In the following examples, the surface of the chloric acid sludge is gray-yellow mud lumps, and its main components and contents are shown in Table 1.

[0095] Table 1 Main components and contents of the chloric acid sludge used in the examples before treatment

[0096] Component <![CDATA[Al 2 O 3 > CaO CuO <![CDATA[TiO 2 > <![CDATA[V 2 O 5 > ZnO MnO <![CDATA[SiO 2 > <![CDATA[Fe 2 O 3 > <![CDATA[Cl - > Water Content / wt% 0.55 1 0.05 0.03 0.1 0.005 1.4 8 42 11 35

[0097] Example 1

[0098] This example provides a method for recovering chloric acid sludge, which is carried out in the Figure 1 shown chloric acid sludge recovery system, and includes the following steps:

[0099] (1) The chloric acid sludge in the filter press falls from the top of the briquetting machine into the briquetting machine by its own gravity, and the chloric acid sludge is extruded by the briquetting machine under a pressure of 35 MPa to obtain acid liquid and formed mud blocks; the size of the formed mud blocks is 1000 mm × 1000 mm × 1000 mm;

[0100] (2) The acid liquid in the chloric acid sludge passes through the overflow valve at the lower water collecting tray of the briquetting machine, and the particles carried in the acid liquid are filtered through a filter to obtain filtrate, and the filtrate is introduced into a transition tank. When the liquid level of the transition tank reaches 90%, an acid pump is automatically started to pump the filtrate into the existing acid regeneration waste acid tank; among them, the acid concentration in the filtrate is 160 g / L; and

[0101] The formed mud blocks are transported to the entrance of the chain conveyor. As the chain conveyor runs, they gradually pass through a heating furnace and are heated at a temperature of 700 °C. The formed mud blocks stay in the heating furnace for an average of 5 minutes to obtain acid-containing waste gas and mud cakes;

[0102] (3) The acid-containing waste gas generated in the heating furnace is introduced into a first cooling mechanism by a first fan, cooled to below 85 °C by circulating cooling water, and then enters the existing pickling washing tower for purification and then recycled to the pickling rinsing section. The remaining waste gas is exhausted to the atmosphere by a second fan; and

[0103] During the heating treatment process, the mud cakes after high-temperature reaction enter the second cooling mechanism under the operation of the chain conveyor and are cooled to 100 °C by air cooling to obtain iron ore.

[0104] The iron ore obtained in Example 1 is yellowish-black massive bricks. The main components and their contents in the iron ore are detected and analyzed. The specific results are shown in Table 2.

[0105] Table 2 Main components and their contents in the iron ore obtained in Example 1

[0106] Component <![CDATA[Al 2 O 3 > CaO CuO <![CDATA[TiO 2 > <![CDATA[V 2 O 5 > ZnO MnO <![CDATA[SiO 2 > <![CDATA[Fe 2 O 3 > <![CDATA[Cl - > Water Content % 1 1.8 0.1 0.2 0.18 0.01 2.4 14.9 78.33 0.6 0.4

[0107] Example 2

[0108] This example provides a method for recovering chloric acid-containing sludge, which is carried out with reference to the method in Example 1, except that: the first pressure in step (1) is 40 MPa.

[0109] The main components and their contents of the iron ore obtained in Example 2 are detected and analyzed. The specific results are shown in Table 3.

[0110] Table 3 Main components and their contents in the iron ore obtained in Example 2

[0111] Component <![CDATA[Al 2 O 3 > CaO Cu <![CDATA[TiO 2 > <![CDATA[V 2 O 5 > ZnO MnO <![CDATA[SiO 2 > <![CDATA[Fe 2 O 3 > <![CDATA[Cl - > Water Content % 1 1.8 0.1 0.2 0.18 0.01 2.4 14.9 78.4 0.5 0.3

[0112] Example 3

[0113] This example provides a method for recovering chloric acid-containing sludge, which is carried out with reference to the method in Example 1, except that: the heating temperature in step (2) is 600 °C.

[0114] The main components and their contents of the iron ore obtained in Example 3 are detected and analyzed. The specific results are shown in Table 4.

[0115] Table 4 Main components and their contents in the iron ore obtained in Example 3

[0116] Component <![CDATA[Al 2 O 3 > CaO Cu <![CDATA[TiO 2 > <![CDATA[V 2 O 5 > ZnO MnO <![CDATA[SiO 2 > <![CDATA[Fe 2 O 3 > <![CDATA[Cl - > Water Content % 0.99 1.79 0.1 0.19 0.18 0.01 2.39 14.8 78 1 0.5

[0117] Comparative Example 1

[0118] This comparative example provides a method for recovering chloric acid-containing sludge, which is carried out with reference to the method in Example 1, except that: the first pressure in step (1) is 30 MPa.

[0119] The main components and their contents of the iron ore obtained in Comparative Example 1 are detected and analyzed. The specific results are shown in Table 5.

[0120] Table 5 Main components and their contents in the iron ore obtained in Comparative Example 1

[0121] Component <![CDATA[Al 2 O 3 > CaO CuO <![CDATA[TiO 2 > <![CDATA[V 2 O 5 > ZnO MnO <![CDATA[SiO 2 > <![CDATA[Fe 2 O 3 > <![CDATA[Cl - > Water Content % 0.97 1.75 0.1 0.19 0.17 0.01 2.3 14.5 76 2.2 1.8

[0122] Comparative Example 2

[0123] This comparative example provides a method for recycling chloric acid-containing mud, which is carried out according to the method in Example 1, with the difference that: the heating temperature in step (2) is 900 °C.

[0124] The main components and their contents of the iron ore obtained in Comparative Example 2 were detected and analyzed, and the specific results are shown in Table 6.

[0125] Table 6 Main components and their contents in the iron ore obtained in Comparative Example 2

[0126] Component <![CDATA[Al 2 O 3 > CaO Cu <![CDATA[TiO 2 > <![CDATA[V 2 O 5 > ZnO MnO <![CDATA[SiO 2 > <![CDATA[Fe 2 O 3 > <![CDATA[Cl - > Water Content % 1 1.8 0.1 0.2 0.18 0.01 2.4 15 78.7 0.3 0.2

[0127] At this high temperature, the forming effect of the mud blocks is poor, and some mud blocks are broken.

[0128] Through comparison, it is found that by adopting the recycling process provided by the present invention, combined with specific pressure and heat treatment, the chloride ion content in the chloric acid-containing mud can be effectively reduced, and other impurities in the acid mud can also be removed, obtaining iron ore with good forming effect and high iron content grade. The whole recycling process is pollution-free, not only saving high treatment costs, but also obtaining high returns from selling iron ore, meeting the requirements of safety and environmental protection.

[0129] In the above technical solution of the present invention, the above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied to other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A method for recovering chloric acid sludge, characterized in that: include: (1) performing solid-liquid separation on the chlorine-containing acid mud under a first pressure condition to obtain acid solution and formed mud blocks; (2) filtering the acid solution to obtain a filtrate, and recycling the filtrate back to the acid regeneration waste acid tank; as well as The formed mud block is subjected to heating treatment to obtain acid-containing waste gas and mud cake; (3) subjecting the acid-containing waste gas to a first cooling treatment and then recycling it back to the acid washing tower; and The mud cake is subjected to a second cooling process to obtain iron ore; Wherein, in step (1), Cl in the chlorine-containing acid mud - The content is not less than 10wt%, and the first pressure is 35-40MPa.

2. The method according to claim 1, characterized in that In step (1), the chloric acid sludge also contains iron trioxide and water, and the iron trioxide content is not less than 40wt%, and the water content is 30-40wt%.

3. The method according to claim 2, characterized in that In step (1), the solid-liquid separation is carried out in a briquetting machine; and / or In step (1), the first pressure and the conditions of the briquetting machine are controlled so that the size of the formed mud block is (900-1000) mm×(900-1000) mm×(900-1000) mm.

4. The method according to claim 1, characterized in that: In step (2), the method further comprises: introducing the filtrate into a transition tank, and using an acid pump to circulate the filtrate in the transition tank back to the acid regeneration waste acid tank; and / or In step (2), the acid concentration in the filtrate is 130-180 g / L.

5. The method according to claim 1, characterized in that In step (2), the conditions for the heating treatment include at least: a temperature of 500-700° C. and a time of not less than 5 minutes.

6. The method according to claim 1, characterized in that In step (3), the conditions of the first cooling treatment are controlled so that the acid-containing waste gas is cooled to 70-85°C.

7. The method according to claim 1, characterized in that In step (3), the conditions of the second cooling treatment are controlled so that the mud cake is cooled to below 100°C.

8. The method according to any one of claims 1 to 7, characterized in that: In step (3), the iron content in the iron ore is not less than 55wt%.

9. A system for recovering chloric acid sludge, characterized in that: include: A pressure device (10), the pressure device (10) is connected to the filter press and is used to provide pressure to separate the chlorine-containing acid mud from the filter press into solid and liquid to obtain acid liquid and formed mud blocks; A filter device (20), one end of the filter device (20) is connected to the pressure device (10), and the other end of the filter device (20) is connected to the acid regeneration waste acid tank (50), and the filter device (20) is used to filter the acid solution obtained by the pressure device (10) and circulate the filtered filtrate back to the acid regeneration waste acid tank (50); A heating device (60), the heating device (60) is used to heat the formed mud block obtained by the pressure device (10) to obtain acid-containing waste gas and mud cake; A cooling device (70), the cooling device (70) comprising a first cooling mechanism (701) and a second cooling mechanism (702), the first cooling mechanism (701) being used for performing a first cooling treatment on the acid-containing waste gas obtained by the treatment of the heating device (60), the second cooling mechanism (702) being used for performing a second cooling treatment on the mud cake obtained by the treatment of the heating device (60), and the first cooling mechanism (701) being connected to the acid washing tower (80).

10. The system according to claim 9, characterized in that The pressure device (10) is a briquetting machine; and / or The filtering device (20) and the acid regeneration waste acid tank (50) are also provided with a transition tank (30) and an acid pump (40) in sequence. The transition tank (30) is used to store the filtrate obtained after filtering by the filtering device (20), and the acid pump (40) is used to pump the filtrate in the transition tank (30) into the acid regeneration waste acid tank (50).

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