Method for energy-saving treatment of ferrous sulfate process waste

Abstract

The invention relates to the technical field of titanium dioxide production, and discloses an energy-saving method for treating ferrous sulfate process waste, which comprises the following steps: mixing titanium concentrate and ferrous sulfate process waste to form mixed ore, and then adding concentrated sulfuric acid for premixing; initiating water is added into the premixed materials, system reaction is initiated and maintained through acid liberation heat release of the titanium concentrate so as to synchronously treat the titanium concentrate and waste in the mixed ore, and curing is conducted after the reaction is completed; and after the reaction product is subjected to leaching and solid-liquid separation, the liquid phase is merged into a titaniferous solution working procedure of sulfuric acid method titanium dioxide production, and the solid phase is merged into acidolysis residue treatment. According to the method disclosed by the invention, the required heat is provided for the endothermic acidolysis reaction of the waste by utilizing the violent exothermic reaction during the acidolysis of the titanium concentrate, and energy complementation in the system is formed, so that the problem of high energy consumption caused by heat complementation in the whole process in a comparison file is avoided, and the operation cost of the treatment process is remarkably reduced; the harmless and resourceful treatment of the waste is realized.

Description

Technical Field

[0001] This invention relates to the field of titanium dioxide production technology, and in particular to an energy-saving method for treating waste from the ferrous sulfate process. Background Technology

[0002] In the titanium dioxide industry, ferrous sulfate is often used to prepare sulfuric acid and other iron byproducts, but this production process generates a certain amount of solid waste. Currently, this waste is usually discarded directly as scrap, which not only wastes resources but also puts pressure on the environment. Analysis shows that the waste contains approximately 23.46% water, and its main components after drying are TiO2 (76%), Fe2O3 (10%), and SO3 (10%). Chemically, it mainly consists of metatitanic acid produced by hydrolysis and incompletely recovered ferrous sulfate / ferrous sulfate, theoretically possessing the potential for acid hydrolysis recovery. XRD analysis confirms that the titanium in it mainly exists in the form of anatase titanium dioxide.

[0003] However, efficient recycling of this waste faces significant challenges. Firstly, the traditional approach involves washing to remove iron impurities and obtain qualified titanium dioxide products. However, due to the unique structure of this waste—a co-precipitate formed by the hydrolysis of titanium oxysulfate and the oxidation of ferrous iron—neither simple water washing nor acid washing can effectively remove iron to below 30 ppm, the requirement for titanium dioxide production. Approximately 4% iron remains. Secondly, if a separate acidolysis process similar to that used for titanium concentrate is considered, two fatal flaws exist: firstly, the material itself contains about 20% moisture, severely diluting the concentration of the reaction acid; secondly, the acidolysis of anatase TiO2 is an endothermic reaction, and the entire material system lacks self-heating capabilities, requiring continuous external heating, resulting in extremely high energy consumption and poor economic efficiency.

[0004] Therefore, there is a need in the existing technology for an energy-efficient method to treat waste from the ferrous sulfate process. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose an energy-saving method for treating ferrous sulfate process waste, achieving harmless treatment and resource recycling of the waste without increasing additional costs or equipment.

[0006] To achieve the above objectives, embodiments of the present invention provide an energy-saving method for treating waste from ferrous sulfate processes, comprising the following steps: S1 mixes titanium concentrate with ferrous sulfate process waste to form a mixed ore, and then adds concentrated sulfuric acid for premixing; S2 adds initiating water to the premixed material, and uses the acid decomposition and heat release of titanium concentrate to initiate and maintain the system reaction in order to simultaneously process titanium concentrate and waste in the mixed ore. After the reaction is completed, it is matured. After leaching and solid-liquid separation, the S3 reaction product is incorporated into the titanium liquid production process of sulfuric acid titanium dioxide, and the solid phase is incorporated into the acid hydrolysis residue treatment.

[0007] In some embodiments, in S1, the mass ratio of waste to titanium concentrate is (0.5~1):100.

[0008] In some embodiments, the concentration of concentrated sulfuric acid in S1 is 94% to 98%.

[0009] In some embodiments, in S1, the premixed acid-to-ore ratio is 1.52 to 1.58, where the acid-to-ore ratio is the mass ratio of concentrated sulfuric acid to the mixed ore.

[0010] In some implementations, in S2, the amount of water initiating the reaction is equal to the amount of acid (concentration of concentrated sulfuric acid) divided by the concentration of the reacting acid (concentration of acid) - the amount of waste (amount of waste) and its water content.

[0011] In some embodiments, in S2, the amount of water added is such that the acid concentration of the reaction system is diluted to 84% to 86%.

[0012] In some embodiments, in S2, the curing is carried out at 160°C to 175°C for 60 min to 90 min.

[0013] In some embodiments, in S3, the leaching operation is as follows: the amount of leaching water is controlled so that the total titanium concentration in the liquid phase is 120 g / L to 140 g / L, and leaching is performed at 60°C to 75°C for 60 min to 120 min.

[0014] In some embodiments, in S1, the titanium dioxide in the waste is anatase.

[0015] In some implementations, in S2, the initiating water is added by spraying within 10-30 seconds.

[0016] The present invention has at least the following beneficial technical effects: (1) Successfully recycled titanium and iron resources from solid waste that were originally to be discarded, with a recycling rate of over 93%, realizing a circular economy and reducing the consumption of primary ore; (2) The intense exothermic reaction during the acidolysis of titanium concentrate is creatively utilized to provide the heat required for the endothermic acidolysis reaction of waste, forming an energy complementarity within the system. This avoids the high energy consumption problem of needing to supplement heat throughout the process as described in the comparative document, and significantly reduces the operating cost of the treatment process. (3) It achieves the harmless and resource-based treatment of waste, reduces the accumulation of solid waste and potential environmental pollution from the source, and has significant environmental benefits without generating new secondary pollution. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of an embodiment of the energy-saving method for treating ferrous sulfate process waste provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0020] 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. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, terms such as “length,” “width,” “upper,” “lower,” “left,” “right,” “front,” “rear,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer” indicate orientations or positions based on the orientations or positions shown in the accompanying drawings and are for ease of description only, and should not be construed as limiting the present invention.

[0021] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., used in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0022] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] like Figure 1 The diagram shown is a schematic representation of an embodiment of the energy-saving method for treating ferrous sulfate process waste provided by the present invention, including the following steps: S1 mixes titanium concentrate with ferrous sulfate process waste to form a mixed ore, and then adds concentrated sulfuric acid for premixing; S2 adds initiating water to the premixed material, and uses the acid decomposition and heat release of titanium concentrate to initiate and maintain the system reaction in order to simultaneously process titanium concentrate and waste in the mixed ore. After the reaction is completed, it is matured. After leaching and solid-liquid separation, the S3 reaction product is incorporated into the titanium liquid production process of sulfuric acid titanium dioxide, and the solid phase is incorporated into the acid hydrolysis residue treatment.

[0024] Further, in S1, the mass ratio of waste to titanium concentrate is (0.5~1):100. The concentration of concentrated sulfuric acid is 94%~98%. The premixed acid-to-ore ratio is 1.52~1.58, which is the mass ratio of concentrated sulfuric acid to the mixed ore. Physically mixing the titanium concentrate with ferrous sulfate process waste (mainly composed of anatase TiO2 and iron salts) aims to ensure a uniform macroscopic distribution of the two materials, creating a homogeneous reaction environment for subsequent chemical reactions. After adding concentrated sulfuric acid, the sulfuric acid will initially wet, penetrate, and react with the surface of the mixture. The strong dehydrating properties of concentrated sulfuric acid can remove some free water from the waste, while simultaneously contacting the metal oxides on the material surface, preheating and activating it for the subsequent vigorous acidolysis reaction. In this step, uniform mixing ensures that the titanium concentrate and waste can react simultaneously and in the same location during the subsequent initiation reaction, avoiding energy and material losses caused by stepwise processing. The premixing process allows sulfuric acid to come into full contact with the materials, shortening the induction period of the subsequent main reaction and making the reaction start up more quickly and thoroughly.

[0025] Furthermore, in S2, the initiating water is added by spraying over 10-30 seconds, and the amount of initiating water added is such that the acid concentration of the reaction system is diluted to 84%~86%. The specific calculation method is as follows: Initiation water volume = Acid volume × Concentrated sulfuric acid concentration ÷ Reaction acid concentration - Acid volume - Waste volume × Waste volume (water content) Furthermore, the curing process is carried out at 160℃~175℃ for 60min~90min.

[0026] The added initiating water is instantly mixed and diluted with concentrated sulfuric acid, releasing a large amount of heat of dilution and causing a rapid temperature rise. This heat first "ignites" the more reactive titanium concentrate. The acidolysis of titanium concentrate is a violent exothermic reaction, and the huge amount of heat released by this reaction is used to compensate for the heat required for the acidolysis of anatase TiO2 in the waste (an endothermic reaction). This forms an internal energy cycle system of "heat-for-heat," using the main reaction (acidolysis of titanium concentrate) to drive the side reaction (acidolysis of waste). High-temperature aging further reacts the intermediate products such as titanium oxysulfate (TiOSO4) generated in the initial reaction to form stable, easily leached solid products. This process is beneficial to improving the titanium conversion rate and the quality of the final product. In this step, efficient synchronous processing of titanium concentrate and waste is achieved in the same reactor and within the same reaction cycle, resulting in an extremely simple process flow. The thorough aging process ensures that titanium and iron in the waste are converted into soluble sulfates to the maximum extent, laying a solid foundation for subsequent high recovery rates (over 93%).

[0027] Further, in step S3, the leaching operation is as follows: the leaching water volume is controlled to maintain the total titanium concentration in the liquid phase at 120 g / L to 140 g / L, and leaching is performed at 60°C to 75°C for 60 to 120 minutes. Under controlled temperature and concentration, the matured solid phase is leached with water. The principle is to utilize the solubility of target products such as titanium oxysulfate and ferric sulfate in water to separate them from insoluble silicate residues. Controlling the total titanium concentration to 120-140 g / L by controlling the leaching water volume ensures that the concentration of the obtained titanium solution matches that of the main process, guaranteeing direct reuse. In this step, the liquid phase is returned to the main process for titanium dioxide production, and the solid phase is treated as residue in the main process, without generating any new secondary waste requiring additional disposal, thus achieving in-situ waste disposal.

[0028] The present invention will be further explained and described below with reference to specific embodiments.

[0029] Example 1 Mix 0.5g of waste with 99.5g of titanium concentrate, add 161.7g of 94% concentrated sulfuric acid and stir (acid-to-ore ratio 1.52). Add 19.15g of water to initiate the reaction (acid concentration 84%). After the reaction is complete (manifested as a slight expansion followed by a drop in volume), place the reactants and reaction vessel in an oven at 160℃ for 60 minutes (aging). After aging, add 200mL of water and heat and stir in a 60℃ water bath for 60 minutes. After the leaching of the reactants is complete, separate the solid and liquid phases using a Buchner funnel. The liquid phase is the purified titanium solution, which can be mixed into the purified titanium solution of the sulfuric acid process as a raw material for the sulfuric acid process titanium dioxide. The residue is mixed into the acid hydrolysis residue of the sulfuric acid process titanium dioxide for further treatment.

[0030] The final acid hydrolysis rate was 93.21%, which is within the normal acid hydrolysis range.

[0031] Example 2 Mix 0.75g of waste with 99.25g of titanium concentrate, add 162.5g of 96% concentrated sulfuric acid and stir (acid-to-ore ratio 1.56). Add 20.89g of water to initiate the reaction (acid concentration 85%). After the reaction is complete (manifested as a slight expansion followed by a drop in volume), place the reactants and reaction vessel in an oven at 170℃ for 60 minutes (aging). After aging, add 200mL of water and heat and stir in a 65℃ water bath for 60 minutes. After the leaching of the reactants is complete, separate the solid and liquid phases using a Buchner funnel. The liquid phase is the purified titanium solution, which can be mixed into the purified titanium solution of the sulfuric acid process as a raw material for the sulfuric acid process titanium dioxide. The residue is mixed into the acid hydrolysis residue of the sulfuric acid process titanium dioxide for further treatment.

[0032] The final acid hydrolysis rate was 93.54%, which is within the normal acid hydrolysis range.

[0033] Example 3 Mix 0.85g of waste with 100g of titanium concentrate, add 161.7g of 94% concentrated sulfuric acid and stir (acid-to-ore ratio 1.52). Add 19.15g of water to initiate the reaction (acid concentration 84%). After the reaction is complete (manifested as a slight expansion followed by a drop in volume), place the reactants and reaction vessel in an oven at 160℃ for 60 minutes (aging). After aging, add 200mL of water and heat and stir in a 60℃ water bath for 60 minutes. After the leaching of the reactants is complete, separate the solid and liquid phases using a Buchner funnel. The liquid phase is the purified titanium solution, which can be mixed into the purified titanium solution of the sulfuric acid process as a raw material for the sulfuric acid process titanium dioxide. The residue is mixed into the acid hydrolysis residue of the sulfuric acid process titanium dioxide for further treatment.

[0034] The final acid hydrolysis rate was 93.89%, which is within the normal acid hydrolysis range.

[0035] Example 4 Mix 1g of waste with 99g of titanium concentrate, add 161.2g of 98% concentrated sulfuric acid and stir (acid-to-ore ratio 1.58). Add 24.45g of water to initiate the reaction (acid concentration 85%). After the reaction is complete (manifested as a slight expansion followed by a drop in volume), place the reactants and reaction vessel in an oven at 170℃ for 60 minutes (aging). After aging, add 200mL of water and heat and stir in a 65℃ water bath for 60 minutes. After the leaching of the reactants is complete, separate the solid and liquid phases using a Buchner funnel. The liquid phase is the purified titanium solution, which can be mixed into the purified titanium solution of the sulfuric acid process as a raw material for the sulfuric acid process titanium dioxide. The residue is mixed into the acid hydrolysis residue of the sulfuric acid process titanium dioxide for further treatment.

[0036] The final acid hydrolysis rate was 94.21%, which is within the normal acid hydrolysis range.

[0037] In summary, since the mixed ore meets the requirements for acidolysis, this invention proposes an innovative method of "mixed ore acidolysis and synergistic treatment." This method involves mixing ferrous sulfate process waste with titanium concentrate in a specific ratio. The heat generated by the vigorous acidolysis and exothermic reaction of the titanium concentrate simultaneously drives the endothermic acidolysis reaction of anatase titanium dioxide in the waste, thereby achieving synergistic treatment of both materials within a single reaction system. This invention successfully solves two core problems inherent in traditional technical approaches: firstly, it overcomes the bottleneck of high energy consumption and poor economic efficiency caused by the need for external heating throughout the acidolysis process; secondly, it avoids the high investment and complex operation associated with constructing independent waste treatment lines.

[0038] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0039] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0040] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0041] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for energy-saving treatment of ferrous sulfate process waste, characterized in that, include: S1 mixes titanium concentrate with ferrous sulfate process waste to form a mixed ore, and then adds concentrated sulfuric acid for premixing; S2 adds initiating water to the premixed material, and uses the acid decomposition and heat release of the titanium concentrate to initiate and maintain the system reaction to simultaneously process the titanium concentrate and waste in the mixed ore. After the reaction is completed, it is matured. After leaching and solid-liquid separation, the S3 reaction product is incorporated into the titanium liquid production process of sulfuric acid titanium dioxide, and the solid phase is incorporated into the acid hydrolysis residue treatment.

2. The method for energy-saving treatment of ferrous sulfate process waste according to claim 1, characterized in that, In S1, the mass ratio of the waste to titanium concentrate is (0.5~1):

100.

3. The method for energy-saving treatment of ferrous sulfate process waste according to claim 1, characterized in that, In S1, the concentration of the concentrated sulfuric acid is 94% to 98%.

4. The method for energy-saving treatment of ferrous sulfate process waste according to claim 3, characterized in that, In S1, the premixed acid-to-ore ratio is 1.52 to 1.58, where the acid-to-ore ratio is the mass ratio of concentrated sulfuric acid to mixed ore.

5. The method for energy-saving treatment of ferrous sulfate process waste according to claim 1, characterized in that, In S2, the amount of water used to initiate the reaction is equal to the amount of acid (concentration of concentrated sulfuric acid) divided by the concentration of the reacting acid (concentration of acid) and the amount of waste (amount of waste with water content).

6. The method for energy-saving treatment of ferrous sulfate process waste according to claim 5, characterized in that, In S2, the amount of water added is such that the acid concentration of the reaction system is diluted to 84%~86%.

7. The method for energy-saving treatment of ferrous sulfate process waste according to claim 1, characterized in that, In S2, the curing is carried out at 160℃~175℃ for 60min~90min.

8. The method for energy-saving treatment of ferrous sulfate process waste according to claim 1, characterized in that, In S3, the leaching operation is as follows: the amount of leaching water is controlled so that the total titanium concentration in the liquid phase is 120g / L~140g / L, and leaching is performed at 60℃~75℃ for 60min~120min.

9. The method for energy-saving treatment of ferrous sulfate process waste according to claim 1, characterized in that, In S1, the titanium dioxide in the waste is anatase.

10. The method for energy-saving treatment of ferrous sulfate process waste according to claim 1, characterized in that, In S2, the initiating water is added by spraying within 10-30 seconds.

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