Composite mineral particles, preparation method therefor and use thereof, and method for treating manganese-containing acidic wastewater to recover manganese oxides

Abstract

Disclosed are composite mineral particles, a preparation method therefor and the use thereof, and a method for treating manganese-containing acidic wastewater to recover manganese oxides. The composite mineral particles are prepared by subjecting preparation raw materials to a hydration reaction, roasting and dehydration condensation, wherein the preparation raw materials comprise bentonite, carbide slag and an excitant. When the composite mineral particles are used for treating manganese-containing acidic wastewater, OH- is continuously released, such that the surfaces of the composite mineral particles are negatively charged to adsorb Mn2+ in the wastewater to form an Mn(OH)2 surface precipitate, which is in contact with dissolved oxygen in the water to generate an autocatalytic oxidation effect, and further by means of the synergistic effect of adsorption-surface precipitation-autocatalytic oxidation by means of contact-aggregation and self-growth, residual composite mineral particles with thin-shell-shaped manganese oxides on the surfaces thereof are obtained, or aggregated and settled manganese oxides and residual composite mineral particles are obtained, thereby realizing the preparation of manganese oxides by means of mineralization and recovery of Mn2+ in the manganese-containing acidic wastewater, and purification treatment of the manganese-containing acidic wastewater.

Description

Composite mineral particles, preparation method and application thereof, and method for treating acidic manganese-containing wastewater and recovering manganese oxides

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on July 18, 2023, with application number CN202310883920.1 and invention name “A composite mineral particle, its preparation method and application, and a method for treating acidic manganese-containing wastewater to recover manganese oxides”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention belongs to the technical field of treating acidic wastewater containing heavy metal ions, and particularly relates to a composite mineral particle, a preparation method and application thereof, and a method for treating acidic manganese-containing wastewater and recovering manganese oxides. Background Art

[0003] With the large-scale mining of manganese ore resources and the rapid development of electrolytic manganese industry, the problem of environmental pollution has become increasingly prominent. In the process of mining, dressing and smelting of manganese ore resources, as well as the discharge of open-air piled waste ore and tailings dams, a large amount of acidic Mn-containing 2+ Wastewater. When metallic manganese is produced by electrolysis, a large amount of electrolytic manganese wastewater is generated. Electrolytic manganese wastewater mainly comes from process cleaning wastewater, electrolytic manganese slag filter press wastewater, electrolytic cell cooling water and plant surface runoff. Since electrolytic manganese is mainly produced by acid soaking method, electrolytic manganese wastewater is acidic with a pH value of about 3 to 6. It has a high content of harmful components and mainly contains high concentrations of sulfates, water-soluble divalent manganese salts, etc. The treatment of electrolytic manganese wastewater is a key issue restricting the development of the manganese industry. These acidic Mn-containing 2+ The wastewater has a large amount of water, strong acidity (pH is 2-6), and heavy metal Mn 2+ High concentration (Mn per liter of water 2+ The content ranges from tens to hundreds of mg), with strong toxicity, wide pollution range, long duration and serious harm, especially the valuable heavy metal Mn 2+ The discharge of wastewater also results in a waste of valuable mineral resources.

[0004] At present, acidic Mn 2+ The main wastewater treatment methods include neutralization, chemical precipitation (hydroxide precipitation, carbonate precipitation, sulfide precipitation), oxidation (natural oxidation, chemical oxidation, contact oxidation), biological methods (biosorption, bioflocculation, constructed wetlands), electrochemical methods (electrochemical oxidation, electroflocculation, electro-Fenton), and physicochemical methods (extraction, ion exchange, membrane filtration, adsorption). However, these treatment methods are difficult to fix and recover manganese ions, resulting in the ineffective mineralization, fixation, and recycling of the valuable metal manganese in the wastewater.

[0005] Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a composite mineral particle and its preparation method and application, and a method for treating acidic manganese-containing wastewater to recover manganese oxides. The composite mineral particle provided by the present invention can recover Mn in acidic manganese-containing wastewater. 2+ Manganese oxides are obtained by mineralization recovery.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The invention provides a composite mineral particle, which is prepared by subjecting raw materials to hydration reaction and roasting dehydration condensation. The raw materials include bentonite, carbide slag and an activator.

[0009] Preferably, the activator comprises sodium carbonate and / or sodium silicate.

[0010] Preferably, the bentonite is sodium bentonite.

[0011] Preferably, the chemical composition of the bentonite includes, by mass percentage: SiO2: 65-80%, Al2O3: 11-17%, Na2O: 3.0-6.0%, CaO: 1.5-3.5%, MgO: 2.0-5.0%, Fe2O3: 1.6-4.0%, K2O: 0.1-1.2%, and impurities: 0.1-2.16%.

[0012] Preferably, the chemical composition of the carbide slag includes, by mass percentage, CaO: 86.7-94.5%, SiO2: 2.0-6.5%, Al2O3: 0.5-3.0%, Fe2O3: 0.2-1.5%, MgO: 0.10-0.22%, and impurities: 0.8-2.32%.

[0013] Preferably, the particle sizes of the bentonite and carbide slag are independently ≤74 μm; and the mass ratio of the bentonite and carbide slag is (20-50):(50-80).

[0014] Preferably, the mass of the activator is 5-9% of the total mass of the bentonite, carbide slag and the activator.

[0015] The present invention also provides a method for preparing the composite mineral particles described in the above technical solution, comprising the following steps:

[0016] performing a first hydration reaction on bentonite, carbide slag and an activator in water to obtain a first hydration reaction product;

[0017] The first hydration reaction product is sequentially granulated, aged, and calcined for dehydration and condensation to obtain composite mineral particles.

[0018] Preferably, before the first hydration reaction, the bentonite and carbide slag are dried; the drying temperature is 100-110° C.; the drying time is 2-4 hours; and the drying is performed until the moisture content of the bentonite and carbide slag is less than 10%.

[0019] Preferably, the mass ratio of the total mass of the bentonite, carbide slag and activator to water is 1:(0.6-0.9).

[0020] Preferably, the granulation is wet granulation; the particle size of the granules obtained by the granulation is 1 to 4 mm.

[0021] Preferably, the aging temperature is 10-35° C. and the aging time is 6-24 hours.

[0022] Preferably, before the roasting dehydration condensation, the process further comprises: preheating the particles obtained by aging; the preheating temperature is 250° C., and the holding time is 10 minutes.

[0023] Preferably, the temperature of the calcination dehydration condensation is 300-500° C., and the holding time is 0.5-1.5 h.

[0024] The present invention also provides the use of the composite mineral particles described in the above technical solution or the composite mineral particles prepared by the preparation method described in the above technical solution in treating acidic manganese-containing wastewater.

[0025] The present invention also provides a method for treating acidic manganese-containing wastewater to recover manganese oxides, comprising the following steps:

[0026] The acidic manganese-containing wastewater is intermittently mixed with the composite mineral particles to perform a second hydration reaction, and the obtained second hydration reaction product undergoes a synergistic action of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation and self-growth on manganese ions in the acidic manganese-containing wastewater to obtain manganese oxides and remaining composite mineral particles;

[0027] The intermittent addition is to add the acidic manganese-containing wastewater 3 to 7 times, with the interval between each two adjacent additions being 1 hour;

[0028] The composite mineral particles are the composite mineral particles described in the above technical solution or the composite mineral particles prepared by the preparation method described in the above technical solution.

[0029] Preferably, the pH value of the acidic manganese-containing wastewater is 2-6; the concentration of divalent manganese ions in the acidic manganese-containing wastewater is 10-700 mg / L; and the amount of the composite mineral particles added per liter of acidic manganese-containing wastewater is 0.01-0.5 g or 1-2 g.

[0030] Preferably, the method further comprises: recycling the manganese oxide as a raw material or finished product; and recycling the remaining composite mineral particles as an adsorbent.

[0031] Preferably, the adsorbent is used to adsorb low-concentration heavy metal ion wastewater; the heavy metal ions in the low-concentration heavy metal ion wastewater are Fe 2+ 、Mn 2+ 、Cu 2+ 、Zn 2+ 、Hg 2+ 、Cd 2+ , Pb 2+ Cr 3+ and Ni 2+ One or more of the following: the concentration of heavy metal ions in the low-concentration heavy metal ion wastewater is 0.1 to 10 mg / L.

[0032] The present invention provides a composite mineral particle, which is prepared by hydration reaction and roasting dehydration condensation of raw materials, wherein the raw materials include bentonite, carbide slag and an activator. When the composite mineral particle provided by the present invention is used to treat acidic manganese-containing wastewater, it continuously releases OH - The surface of the catalyst is negatively charged, thereby adsorbing Mn in the acidic manganese-containing wastewater. 2+ The surface precipitation of Mn(OH)2 is formed, and the self-catalytic oxidation occurs when it contacts with the dissolved oxygen in the water. The surface of the residual composite mineral particles with thin shell-like manganese oxides (mainly containing Mn3O4 and MnO2) are obtained through the synergistic effect of adsorption-surface precipitation-contact self-catalytic oxidation-aggregation and self-growth, or the aggregated manganese oxides (mainly containing Mn3O4 and MnO2) and the remaining composite mineral particles are obtained, so as to realize the removal of Mn in acidic manganese-containing wastewater. 2+ Mineralization recovery to produce manganese oxides and purification of acidic manganese-containing wastewater, and can realize the resource utilization of industrial solid waste carbide slag, turning waste into treasure, treating waste with waste, simultaneous treatment of wastewater and waste slag, and mineralization fixed recovery and circular economy of valuable metal resources in wastewater.

[0033] The present invention also provides a preparation method of the above-mentioned composite mineral particles, which comprises the following steps: mixing bentonite, carbide slag and an activator, causing a hydration reaction under the action of water to form a calcium silicate hydrate (CSH) gel, thereby improving the cohesiveness and mechanical strength of the particles; aging the particles obtained after the hydration reaction and granulation to make the hydration reaction in the particles more complete and the cohesiveness stronger; and dehydrating and condensing the water in the calcium silicate hydrate (CSH) gel by roasting to dehydrate and condense the particles, thereby making the particles condense and bond more tightly and firmly with the carbide slag, etc. When the composite particles are placed in water during use, they slowly absorb water, cause a hydration reaction, and generate the calcium silicate hydrate (CSH) gel again, and continuously and slowly release Ca(OH)2 to make the particle surface carry OH. -Negative charge adsorption of heavy metal Mn 2+ Mn(OH)2 precipitation is generated, dissolved oxygen and Mn 2+ The Mn(OH)2 precipitate on the particle surface is in contact with the particle surface to produce manganese oxides Mn3O4 and MnO2 through autocatalytic oxidation, and the Mn(OH)2 precipitate is in contact with the particle surface to produce manganese oxides Mn3O4 and MnO2 through autocatalytic oxidation. 2+ The synergistic effect of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation and self-growth occurs, and the previously generated Mn3O4 and MnO2 synergistic composite mineral particles continue to play the synergistic effect of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation and self-growth by intermittently adding water, and finally generate residual composite mineral particles mainly in the form of thin shell manganese oxides (mainly containing Mn3O4 and MnO2), or when the amount of composite mineral particles used is large, aggregated manganese oxides (mainly containing Mn3O4 and MnO2) and residual composite mineral particles are generated, and the residual composite mineral particles with thin shell manganese oxides on the surface are recovered, or the thin shell manganese oxides are separated from the residual composite mineral particles and recovered separately, or the aggregated manganese oxides are separated from the residual composite mineral particles and recovered separately, thereby realizing the neutralization and purification of acidic manganese-containing wastewater and the treatment of Mn 2+ Mineralization recovery and production of manganese oxides (mainly containing Mn3O4, MnO2). Experimental results show that the Mn in the acidic manganese-containing wastewater provided by the present invention 2+ The method of mineralization recovery to prepare manganese oxides is to treat acidic wastewater with an initial pH value of 2 to 6 and a heavy metal ion concentration of 10 to 700 mg / L to prepare high-purity manganese oxides (mainly containing Mn3O4, MnO2), Mn 2+ The mineralization recovery amount reaches 100-600 mg / g, the manganese content in manganese oxides reaches more than 40%-76%, and the valuable metal Mn 2+ The mineralization fixation recovery effect is good; when the dosage of composite mineral particles is 1.0-2.0g per liter of wastewater, the effluent pH can reach 6-9, the heavy metal removal rate can reach 95-100%, and the discharge can meet the standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a flow chart of a method for preparing composite mineral particles according to an embodiment of the present invention;

[0035] FIG2 is a diagram of bentonite, a raw material of the present invention;

[0036] FIG3 is a diagram of raw material carbide slag of the present invention;

[0037] FIG4 is a diagram of composite mineral particles prepared in Example 3 of the present invention;

[0038] Figure 5 shows the composite mineral particles obtained in Example 1 of the present invention for treating acidic Mn-containing 2+SEM image of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment;

[0039] FIG6 shows the composite mineral particles obtained in Example 1 of the present invention for treating acidic Mn-containing 2+ EDS images of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment;

[0040] FIG7 shows the composite mineral particles obtained in Example 2 of the present invention for treating acidic Mn-containing 2+ SEM image of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment;

[0041] FIG8 shows the composite mineral particles obtained in Example 2 of the present invention for treating acidic Mn-containing 2+ EDS images of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment;

[0042] FIG9 shows the composite mineral particles obtained in Example 2 of the present invention for treating acidic Mn-containing 2+ XRD pattern of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment;

[0043] FIG10 is a graph showing the composite mineral particles prepared in Example 3 of the present invention for treating acidic Mn-containing 2+ Figure of composite mineral particles after wastewater;

[0044] FIG11 is a SEM image of the composite mineral particles prepared in Example 3 of the present invention;

[0045] Figure 12 shows the treatment of the composite mineral particles prepared in Example 3 of the present invention, which contain acidic Mn 2+ SEM images of composite mineral particles after wastewater treatment;

[0046] FIG13 is an EDS graph of the composite mineral particles prepared in Example 3 of the present invention;

[0047] FIG14 is a graph showing the composite mineral particles prepared in Example 3 of the present invention for treating acidic Mn-containing 2+ EDS images of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment;

[0048] Figure 15 shows the composite mineral particles prepared in Example 3 of the present invention for treating acidic Mn-containing 2+ XPS full spectrum comparison chart before and after wastewater treatment;

[0049] FIG16 is a graph showing the composite mineral particles prepared in Example 3 of the present invention for treating acidic Mn-containing 2+ XPS O 1s high-resolution spectrum of the residual composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment;

[0050] Figure 17 shows the composite mineral particles prepared in Example 3 of the present invention for treating acidic Mn-containing 2+ XPS high-resolution Mn 2p spectrum of the residual composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment;

[0051] FIG18 is a graph showing the composite mineral particles prepared in Example 4 of the present invention for treating acidic Mn-containing 2+ The effect diagram of the coprecipitated manganese oxides generated after wastewater treatment;

[0052] Figure 19 shows the composite mineral particles prepared in Example 4 of the present invention for treating acidic Mn-containing 2+ SEM image of the precipitated manganese oxides generated after wastewater treatment;

[0053] FIG20 is a graph showing the composite mineral particles prepared in Example 4 of the present invention for treating acidic Mn-containing 2+ EDS diagram of the precipitated manganese oxides generated after wastewater treatment;

[0054] Figure 21 is an XRD pattern of the composite mineral particles before and after calcination in Example 3 of the present invention, wherein 1-Ca(OH)2, 2-CaCO3, 3-CSH, 4-MMT, 5-Na2(CaCO3)2·5H2O;

[0055] FIG22 is a graph showing the composite mineral particles prepared in Comparative Example 4 of the present invention for treating acidic Mn-containing 2+ Wastewater diagram. DETAILED DESCRIPTION

[0056] The invention provides a composite mineral particle which is prepared by subjecting raw materials to hydration reaction and roasting dehydration condensation. The raw materials include bentonite, carbide slag, an activator and water.

[0057] Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used, and commercially available products known to those skilled in the art can be used.

[0058] The composite mineral particles provided by the present invention are prepared by subjecting raw materials to hydration reaction and roasting dehydration condensation. The raw materials include bentonite, carbide slag, an activator and water.

[0059] In the present invention, the bentonite is preferably sodium bentonite; the chemical composition of the bentonite preferably includes, by mass percentage, SiO2: 65-80%, Al2O3: 11-17%, Na2O: 3.0-6.0%, CaO: 1.5-3.5%, MgO: 2.0-5.0%, Fe2O3: 1.6-4.0%, K2O: 0.1-1.2%, and impurities: 0.1-2.16%, and more preferably, SiO2: 74.64%, Al2O3: 14.56%, Na2O: 3.61%, CaO: 1.83%, MgO: 3.15%, Fe2O3: 1.63%, K2O: 0.43%, and impurities: 0.15%. The present invention limits the chemical composition of the bentonite to the above range, which is more conducive to the subsequent hydration reaction of the composite mineral particles, thereby improving the Mn 2+ Mineralization recovery to produce manganese oxides.

[0060] In the present invention, the chemical composition of the carbide slag preferably includes, by mass percentage, CaO: 86.7-94.5%, SiO2: 2.0-6.5%, Al2O3: 0.5-3.0%, Fe2O3: 0.2-1.5%, MgO: 0.10-0.22%, and impurities: 0.8-2.32%, and more preferably includes: CaO: 90.34%, SiO2: 5.43%, Al2O3: 2.90%, Fe2O3: 0.21%, MgO: 0.15%, and impurities: 0.97%. The present invention limits the chemical composition of the carbide slag to the above range, which is more conducive to the subsequent hydration reaction of the composite particles, and further to the Mn 2+ Mineralization recovery to produce manganese oxides.

[0061] In the present invention, the particle size of the bentonite and carbide slag is preferably ≤74 μm. The present invention limits the particle size of the bentonite and carbide slag to the above range, which can be beneficial to the subsequent hydration reaction and further promote the composite mineral particles to slowly and continuously release Ca(OH)2 in acidic wastewater to form surface OH - Negatively charged particles, and continuously mineralize and fix heavy metal Mn through adsorption, precipitation, contact autocatalytic oxidation, aggregation and self-growth synergistic action 2+ If the particle size of bentonite and carbide slag exceeds the above range, the prepared composite mineral particles will not be able to continuously remove Mn in acidic wastewater. 2+ Mineralization recovery to produce manganese oxides.

[0062] In the present invention, when the particle sizes of the bentonite and carbide slag do not meet the above requirements, the bentonite and carbide slag are preferably pretreated separately; the pretreatment preferably includes drying, grinding, and screening in sequence. The present invention does not particularly limit the drying, grinding, and screening operations; commonly used operations in the art can be used to achieve a particle size of ≤74 μm for the bentonite and carbide slag.

[0063] In the present invention, the mass ratio of bentonite to carbide slag is preferably (20-50): (50-80), more preferably (20-40): (60-80), and most preferably (20-30): (70-80). The present invention limits the mass ratio of bentonite to carbide slag to the above range, which can improve the performance of composite mineral particles in Mn 2+ The ability to produce manganese oxides through mineralization recovery.

[0064] In the present invention, the activator preferably comprises sodium carbonate and / or sodium silicate, more preferably sodium carbonate; the mass of the activator is preferably 5-9% of the total mass of the bentonite, carbide slag, and activator, more preferably 5.5-8%, and most preferably 6-7%. The present invention limits the amount of the activator to the above range, which can fully stimulate the hydration reaction without wasting raw materials and saving resources.

[0065] In the present invention, the main components of the composite mineral particles before calcination include Ca(OH)2, CaCO3, and calcium silicate (calcium silicate is hydrated calcium silicate (CSH)), which are dehydrated and condensed after calcination to form amorphous calcium silicate 3CaO·SiO2 or 2CaO·SiO2.

[0066] The present invention also provides a method for preparing the composite mineral particles described in the above technical solution, comprising the following steps:

[0067] Performing a first hydration reaction of bentonite, carbide slag and an activator in water to obtain a first hydration product;

[0068] The first hydration product is sequentially granulated, aged, and calcined for dehydration and condensation to obtain composite mineral particles.

[0069] The present invention conducts a first hydration reaction on bentonite, carbide slag and an activator in water to obtain a first hydration reaction product.

[0070] Before the first hydration reaction, the present invention preferably dries the bentonite and carbide slag; the drying is preferably oven drying; the drying equipment is preferably an oven; the drying temperature is preferably 100-110°C, more preferably 105°C; the drying time is preferably 2-4 hours, more preferably 2-3 hours; and the drying is preferably performed until the moisture content of the bentonite and carbide slag is less than 10%. The present invention has no particular requirements for the model of the oven; ovens commonly used in the art can be used. By limiting the drying temperature and time within the above ranges, the bentonite and carbide slag can be fully dried.

[0071] In the present invention, the step of performing a first hydration reaction of bentonite, carbide slag, and an activator in water preferably includes: first mixing the bentonite, carbide slag, and activator, and then adding water for a second mixing. The present invention does not particularly limit the specific operation of the first mixing, as long as the bentonite, carbide slag, and activator are uniformly mixed. The present invention limits the mixing of the bentonite, carbide slag, and activator with water to the above order to facilitate the hydration reaction.

[0072] In the present invention, the mass ratio of the total mass of the bentonite, carbide slag and activator to water is preferably 1:(0.6-0.9), more preferably 1:(0.7-0.9). In the present invention, limiting the mass ratio of the total mass of the bentonite, carbide slag and activator to water to the above range can facilitate the hydration reaction.

[0073] In the present invention, the first mixing is preferably performed under mechanical stirring conditions; the mechanical stirring is preferably performed using a mechanical stirrer. The present invention does not particularly limit the type of mechanical stirrer; any mechanical stirrer known in the art can be used. The present invention does not particularly limit the first mixing temperature and time; any temperature sufficient to uniformly mix the bentonite, carbide slag, and activator is sufficient.

[0074] In the present invention, the second mixing is preferably performed under mechanical stirring conditions; the mechanical stirring is preferably performed using a mechanical stirrer; the second mixing time is preferably 10 to 20 minutes, more preferably 15 minutes. The present invention does not particularly limit the type of mechanical stirrer; any model familiar to those skilled in the art can be used. The second mixing can further enhance the hydration reaction.

[0075] The present invention mixes dry bentonite, carbide slag and an activator. When CaO and Ca(OH)2 in the dry carbide slag come into contact with water H2O, they will be hydrolyzed to generate Ca(OH)2 and release a large amount of heat, which is conducive to the hydration reaction to form a large amount of calcium silicate hydrate (CSH) gel, which can improve the cohesiveness and mechanical strength of the particles. The specific reaction in the hydration process is shown in the following formula: Na2CO3+Ca(OH)2=2NaOH+CaCO3↓2NaOH+SiO2=Na2SiO3+H2O Na2SiO3+Ca(OH)2+nH2O=2NaOH+CaSiO3·nH2O(CSH).

[0076] After obtaining the first hydration reaction product, the present invention granulates the first hydration reaction product.

[0077] In the present invention, the granulation is preferably wet granulation; the equipment used for the granulation is preferably a forming granulator; the particle size of the granules obtained by the granulation is preferably 1 to 4 mm, more preferably 2 to 3 mm. The present invention has no special restrictions on the setting of the process parameters for granulation, and the parameters well known in the art can be used to obtain a particle size that meets the requirements. The present invention limits the particle size of the granules obtained by granulation to the above range to improve the Mn 2+ The effect of mineralization recovery in producing manganese oxides.

[0078] After the granulation, the present invention ages the granules obtained by the granulation to obtain aged granules.

[0079] In the present invention, the aging temperature is preferably 10 to 35°C, more preferably 20 to 25°C, and the time is preferably 6 to 24 hours, more preferably 12 to 18 hours. The present invention sets the aging temperature within the above range to make the hydration reaction more sufficient. The present invention can make the composite mineral particles slowly and continuously release Ca(OH)2 in acidic wastewater to form surface OH - Negatively charged particles are beneficial to Mn 2+ Mineralization recovery to produce manganese oxides.

[0080] In the present invention, the granules obtained by granulation are preferably covered with plastic cloth during the aging process. The present invention can avoid water loss during the aging process by covering, thereby ensuring the amount of water required for the hydration reaction.

[0081] After obtaining the aged particles, the present invention performs roasting, dehydration and condensation on the aged particles to obtain composite mineral particles.

[0082] Before performing the roasting dehydration condensation, the present invention preferably further comprises: preheating the particles obtained by aging.

[0083] In the present invention, the preheating temperature is preferably 250°C and the holding time is 10 minutes; the preheating is preferably carried out in a muffle furnace. The present invention uses preheating to avoid cracking of particles caused by too high a starting temperature for calcination.

[0084] In the present invention, the calcination-dehydration-condensation temperature is preferably 300-500°C, more preferably 350-450°C, and the holding time is preferably 0.5-1.5 hours, more preferably 1 hour. The calcination-dehydration-condensation is preferably carried out in a muffle furnace. Bentonite, carbide slag, and an activator react with water to form hydrated calcium silicate. The resulting hydrated calcium silicate (CSH) gel undergoes dehydration and condensation after calcination to form amorphous calcium silicate 3CaO·SiO2 or 2CaO·SiO2, which is tightly and firmly bonded to Ca(OH)2 and other substances.

[0085] The present invention has no special requirements for the model of the muffle furnace, and a muffle furnace commonly used in the art can be used. The present invention sets the temperature and time of preheating, roasting, dehydration and condensation within the above range, which can make the composite mineral particles fully sintered, dehydrated and condensed, and the materials inside the particles are tightly and firmly combined, which is conducive to the subsequent slow and continuous release of Ca(OH)2 by the composite mineral particles in acidic wastewater to form surface OH - Negatively charged particles. The present invention can make the composite particles undergo hydration reaction in acidic wastewater by preheating, roasting, dehydration and condensation, slowly and continuously releasing Ca(OH)2 to form surface OH - Negatively charged particles can better achieve the removal of Mn in acidic wastewater 2+ Mineralization recovery to produce manganese oxides.

[0086] The present invention preferably performs a cooling treatment on the product after the roasting, dehydration and condensation; the cooling treatment is preferably natural cooling. The present invention can facilitate the preservation of the composite mineral particles through the cooling treatment.

[0087] FIG1 is a flow chart of a method for preparing composite mineral particles according to an embodiment of the present invention. As shown in FIG1 , the present invention sequentially dries, grinds, screens, and oven-dries bentonite and carbide slag, then weighs, stirs, and mixes them with an activator in proportion. Water is then added in proportion and stirred evenly to cause a hydration reaction. Granulation, covering with plastic sheeting for moisture retention, aging, preheating, roasting, and finally, natural cooling are performed to produce composite mineral particles.

[0088] The present invention also provides the use of the composite mineral particles described in the above technical solution or the composite mineral particles prepared by the preparation method described in the above technical solution in treating acidic manganese-containing wastewater.

[0089] The present invention also provides a method for treating acidic manganese-containing wastewater to recover manganese oxides, comprising the following steps:

[0090] The acidic manganese-containing wastewater is intermittently mixed with the composite mineral particles to perform a second hydration reaction, and the obtained second hydration reaction product undergoes a synergistic action of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation and self-growth on manganese ions in the acidic manganese-containing wastewater to obtain manganese oxides and remaining composite mineral particles;

[0091] The intermittent addition is to add the acidic manganese-containing wastewater 3 to 7 times, with the interval between each two adjacent additions being 1 hour;

[0092] The composite mineral particles are the composite mineral particles described in the above technical solution or the composite mineral particles prepared by the preparation method described in the above technical solution.

[0093] In the present invention, the pH value of the acidic manganese-containing wastewater is preferably 2 to 6, more preferably 3 to 5; the concentration of divalent manganese ions in the acidic manganese-containing wastewater is preferably 10 to 700 mg / L, more preferably 100 to 300 mg / L; the amount of the composite mineral particles added per liter of acidic manganese-containing wastewater is preferably 0.01 to 0.5 g or 1 to 2 g.

[0094] The present invention adds 0.01-0.5g of composite mineral particles per liter of acidic manganese-containing wastewater, which can better treat Mn in the wastewater. 2+ Mineralization recovery to produce thin shell-like manganese oxides (mainly containing Mn3O4, MnO2) and particles;

[0095] Alternatively, the present invention adds 1 to 2 g of composite mineral particles per liter of acidic manganese-containing wastewater to release more Ca(OH)2 to neutralize H in the acidic manganese-containing wastewater. + , and excess OH - Diffusion into the water sample and Mn 2+ The Mn(OH)2 precipitate formed in the water sample continuously contacts and collides with the Mn(OH)2 precipitate formed on the particle surface, undergoes self-catalytic oxidation, aggregation and self-growth, and coagulation, which can better remove the Mn in the wastewater. 2+ Mineralization recovery is used to produce precipitated manganese oxides (mainly containing Mn3O4, MnO2) and remaining composite mineral particles.

[0096] When the dosage of the composite mineral particles per liter of acidic manganese-containing wastewater is small, the alkalinity release is small, and adsorption-precipitation-contact autocatalytic oxidation-aggregation self-growth synergistically occurs only on the surface of the particles to form a thin shell-like manganese oxide; when the dosage is large, the alkalinity release is large, and the alkalinity diffuses into the water sample, and adsorption-precipitation occurs both on the particle surface and in the water sample, and under the condition of a stirring speed of 100 to 150 revolutions, contact autocatalytic oxidation-aggregation self-growth synergistically occurs to form a precipitated substance, forming a precipitated manganese oxide.

[0097] In the present invention, the manganese oxide is preferably a thin shell-like manganese oxide or a precipitated manganese oxide wrapped on the surface of the remaining composite mineral particles; the components of the manganese oxide are mainly Mn3O4 and MnO2. The present invention achieves the synergistic effect of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation self-growth to remove heavy metal Mn. 2+ The surface color of the remaining composite mineral particles is substantially the same as that of the composite mineral particles, and contains a small amount of manganese oxides.

[0098] In the present invention, the remaining composite mineral particles are preferably particles having a loose porous structure after the composite mineral particles undergo a hydration reaction to release Ca(OH)2.

[0099] In the present invention, the intermittent addition of the acidic manganese-containing wastewater is 3 to 7 times, preferably 4 to 6 times, and the interval between each two adjacent additions is 1 hour; the present invention limits the intermittent addition of water to 4 to 6 times, and through the intermittent addition of water, the previously generated Mn3O4 and MO2 can be fully utilized to cooperate with the composite mineral particles to continue to play a role in Mn 2+ The synergistic effect of adsorption-surface precipitation-contact self-catalytic oxidation-aggregation self-growth can better achieve the removal of Mn in wastewater. 2+ Mineralization recovery produces thin shell-like manganese oxides (mainly containing Mn3O4, MnO2) and remaining composite mineral particles or precipitated manganese oxides (mainly containing Mn3O4, MnO2) and remaining composite mineral particles. The present invention limits the interval of each water addition to 1 hour to ensure that the Mn(OH)2 precipitate generated each time has sufficient contact with dissolved oxygen and the autocatalytic oxidation reaction time can better achieve the Mn in wastewater. 2+ Mineralization recovery produces thin shell-like manganese oxides (mainly containing Mn3O4, MnO2) and remaining composite mineral particles or precipitated manganese oxides (mainly containing Mn3O4, MnO2) and remaining composite mineral particles.

[0100] In the present invention, the second hydration reaction is preferably carried out under stirring conditions; the stirring rate is preferably 100-150 r / min, more preferably 100-120 r / min. When the composite mineral particles are mixed with wastewater, they slowly absorb water and undergo hydration reaction to generate hydrated calcium silicate (CSH) gel again, and continuously and slowly release Ca(OH)2 to make the particle surface carry OH - Negative charge adsorption of heavy metal Mn 2+ The invention limits the rotation speed to 100-150 r / min, so that the dissolved oxygen and Mn in water are 2+ The particles are in better contact with the Mn(OH)2 precipitate on the surface of the particles to generate manganese oxides Mn3O4 and MnO2 through autocatalytic oxidation, and continue to 2+A synergistic effect of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation and self-growth occurs, and ultimately residual composite mineral particles mainly in the form of thin shell-like manganese oxides (mainly containing Mn3O4 and MnO2) are generated, or when the amount of composite mineral particles is large, aggregated manganese oxides (mainly containing Mn3O4 and MnO2) and residual composite mineral particles are generated.

[0101] After obtaining the manganese oxide, the present invention preferably discharges the treated acidic manganese-containing wastewater, collects and dries the manganese oxide and remaining composite mineral particles, and then separates and recovers the manganese oxide and remaining composite mineral particles. When the manganese oxide is in the form of a thin shell coated on the surface of the remaining composite mineral particles, the present invention preferably utilizes an oscillator to separate the thin shell-like manganese oxide coated on the surface of the remaining composite mineral particles from the particles, and then recovers the two separately. The present invention does not particularly limit the specific operation of the oscillator, as long as the thin shell-like manganese oxide can be separated from the particles.

[0102] In the present invention, the drying is preferably carried out under natural conditions for 48 to 72 hours or at high temperature; the high temperature drying is preferably carried out in an oven; the temperature of the high temperature drying is preferably 105°C, and the high temperature drying time is preferably 3 to 4 hours. The present invention does not particularly limit the model of the oven; an oven commonly used in the art can be used. The present invention limits the drying temperature and time to the above ranges to fully dry the remaining composite mineral particles of the thin shell-like manganese oxide (mainly containing Mn3O4 and MnO2) or the precipitated manganese oxide (mainly containing Mn3O4 and MnO2) and the remaining composite mineral particles.

[0103] In the present invention, it is preferred that the method further comprises: recycling the manganese oxide as a raw material or finished product, more preferably as a manganese battery material, a photocatalyst, a raw material for manganese oxide, a raw material for electrolytic manganese, a raw material for smelting heavy metals, or a pigment; when the manganese oxide is a thin shell-like manganese oxide wrapped on the surface of the remaining composite mineral particles, the manganese oxide is more preferably recycled as a manganese battery material or a photocatalyst;

[0104] In the present invention, it is preferred that the remaining composite mineral particles are preferably recycled and used as an adsorbent; the adsorbent is preferably used to adsorb low-concentration heavy metal ion wastewater. In the present invention, the heavy metal ions in the low-concentration heavy metal ion wastewater are preferably Fe 2+ 、Mn 2+ 、Cu 2+ 、Zn 2+ 、Hg 2+ 、Cd 2+ , Pb 2+ Cr 3+ and Ni 2+The concentration of heavy metal ions in the low-concentration heavy metal ion wastewater is preferably 0.1 to 10 mg / L, more preferably 1 to 5 mg / L. The present invention achieves zero waste discharge, green and environmentally friendly recycling by separately recovering manganese oxides and residual composite mineral particles, and can also achieve a circular economy.

[0105] In the present invention, when the adsorbent reaches saturation with heavy metal ions in low-concentration heavy metal wastewater, the saturated adsorbent is preferably dried and recycled as a metal mineral resource. This invention utilizes the increased porosity and surface area of ​​the particles obtained after the hydration reaction, making them more suitable for use as an adsorbent and easily recyclable. This process eliminates waste, is environmentally friendly, and contributes to a circular economy.

[0106] In the present invention, the drying is preferably carried out under natural conditions for 48-72 hours or at high temperature; the high-temperature drying is preferably carried out in an oven; the temperature of the high-temperature drying is preferably 105°C, and the high-temperature drying time is preferably 3-4 hours. The present invention does not particularly limit the type of oven; ovens commonly used in the art can be used. The present invention limits the drying temperature and time to the above ranges to fully dry the adsorbent after saturation.

[0107] The present invention provides Mn in acidic manganese-containing wastewater 2+ The method of mineralization recovery to prepare manganese oxides is to adjust the particle size of bentonite and carbide slag, mix them with an activator, and generate a hydration reaction under the action of water to form hydrated calcium silicate (CSH) gel, etc., thereby improving the cohesiveness and mechanical strength of the particles; the particles obtained after the hydration reaction and granulation are aged to make the hydration reaction in the particles more complete, and the water in the hydrated calcium silicate (CSH) gel is dehydrated by preheating, roasting and dehydration condensation to cause the particles to sinter and condense. When the composite mineral particles after dehydration, sintering and condensation are placed in water during use, they slowly absorb water and generate a hydration reaction to generate hydrated calcium silicate (CSH) gel again, and continuously and slowly release Ca(OH)2 to make the particle surface carry OH - Negative charge adsorption of heavy metal Mn 2+ Mn(OH)2 precipitation is generated. Under the stirring condition of 100-150r / min, dissolved oxygen and Mn 2+ The Mn(OH)2 precipitate on the particle surface is in contact with the particle surface to produce manganese oxides Mn3O4 and MnO2 through autocatalytic oxidation, and the Mn(OH)2 precipitate is in contact with the particle surface to produce manganese oxides Mn3O4 and MnO2 through autocatalytic oxidation. 2+A synergistic effect of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation and self-growth occurs, and by intermittent addition of water, the previously generated Mn3O4 and MnO2 synergistic composite mineral particles continue to play a synergistic role of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation and self-growth, and finally residual composite mineral particles mainly in the form of thin shell manganese oxides (mainly containing Mn3O4 and MnO2) are generated, or when the amount of composite mineral particles used is large, aggregated manganese oxides (mainly containing Mn3O4 and MnO2) and residual composite mineral particles are generated, and the residual composite mineral particles with thin shell manganese oxides on the surface or the thin shell manganese oxides are separated from the residual composite mineral particles and recovered separately, or the aggregated manganese oxides and the residual composite mineral particles are separated and recovered separately.

[0108] The technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention, but they should not be understood as limiting the scope of protection of the present invention.

[0109] Example 1

[0110] The preparation method of the composite mineral particles comprises the following steps:

[0111] The bentonite and carbide slag are dried in an oven at 105°C for 3 hours until the moisture content is less than 10%, and then mixed with sodium carbonate in a mechanical stirrer. Water is then added and mixed for 15 minutes for hydration reaction. Then, a granulator is used to make particles with a diameter of 2 mm and a length of 3 mm. The granulated particles are covered with plastic cloth and aged at 20°C for 10 hours. Then, the particles are placed in a muffle furnace with a preheating temperature of 250°C and continue to be heated to 400°C and a roasting time of 0.6 hours is started. After the roasting is completed, the particles are naturally cooled to obtain composite mineral particles; the particle size of the bentonite and carbide slag is independently ≤74μm; the mass ratio of the bentonite and carbide slag is 20:80; the mass of the sodium carbonate accounts for 10% of the mass of the bentonite, carbide slag and 7wt.% of the total mass of sodium carbonate; the mass ratio of the total mass of the bentonite, carbide slag and sodium carbonate to water is 1:0.9; the chemical composition of the bentonite is as follows by mass percentage: SiO2: 74.64%, Al2O3: 14.56%, Na2O: 3.61%, CaO: 1.83%, MgO: 3.15%, Fe2O3: 1.63%, K2O: 0.43%, others: 0.15%; the chemical composition of the carbide slag is as follows by mass percentage: CaO: 90.34%, SiO2: 5.43%, Al2O3: 2.90%, Fe2O3: 0.21%, MgO: 0.15%, impurities: 0.97%.

[0112] Example 2

[0113] The preparation method of the composite mineral particles comprises the following steps:

[0114] The bentonite and carbide slag are dried in an oven at 105°C for 3 hours until the moisture content is less than 10%, and then mixed with sodium carbonate in a mechanical stirrer. Water is then added and mixed for 15 minutes for hydration reaction. Then, a granulator is used to make particles with a diameter of 2 mm and a length of 3 mm. The particles obtained by granulation are covered with plastic cloth and aged at 20°C for 12 hours. Then, the particles are placed in a muffle furnace with a preheating temperature of 250°C and continue to be heated to 400°C and a roasting time of 0.6 hours is started. After the roasting is completed, the particles are naturally cooled to obtain composite mineral particles; the particle size of the bentonite and carbide slag is independently ≤74μm; the mass ratio of the bentonite and carbide slag is 20:80; the mass of the sodium carbonate accounts for 10% of the mass of the bentonite, carbide slag and 6wt.% of the total mass of sodium carbonate; the mass ratio of the total mass of the bentonite, carbide slag and sodium carbonate to water is 1:0.9; the chemical composition of the bentonite is as follows by mass percentage: SiO2: 74.64%, Al2O3: 14.56%, Na2O: 3.61%, CaO: 1.83%, MgO: 3.15%, Fe2O3: 1.63%, K2O: 0.43%, others: 0.15%; the chemical composition of the carbide slag is as follows by mass percentage: CaO: 90.34%, SiO2: 5.43%, Al2O3: 2.90%, Fe2O3: 0.21%, MgO: 0.15%, impurities: 0.97%.

[0115] Example 3

[0116] The preparation method of the composite mineral particles comprises the following steps:

[0117] The bentonite and carbide slag are dried in an oven at 105°C for 3 hours until the moisture content is less than 10%, and then mixed with sodium carbonate in a mechanical stirrer. Water is then added and mixed for 15 minutes to carry out a second hydration reaction. Then, a granulator is used to make particles with a diameter of 2 mm and a length of 3 mm. The granulated particles are covered with plastic cloth and aged at 20°C for 15 hours. Then, the particles are placed in a muffle furnace with a preheating temperature of 250°C and continuously heated to 400°C and a roasting time of 0.6 hours is started. After the roasting is completed, the particles are naturally cooled to obtain composite mineral particles; the particle size of the bentonite and carbide slag is independently ≤74μm; the mass ratio of the bentonite and carbide slag is 25:75; the mass of the sodium carbonate accounts for 10% of the mass of the bentonite and carbide slag and sodium carbonate; the mass ratio of the total mass of the bentonite, carbide slag and sodium carbonate to water is 1:0.7; the chemical composition of the bentonite is as follows by mass percentage: SiO2: 74.64%, Al2O3: 14.56%, Na2O: 3.61%, CaO: 1.83%, MgO: 3.15%, Fe2O3: 1.63%, K2O: 0.43%, others: 0.15%; the chemical composition of the carbide slag is as follows by mass percentage: CaO: 90.34%, SiO2: 5.43%, Al2O3: 2.90%, Fe2O3: 0.21%, MgO: 0.15%, impurities: 0.97%.

[0118] Example 4

[0119] The preparation method of the composite mineral particles comprises the following steps:

[0120] The bentonite and carbide slag are dried in an oven at 105°C for 3 hours until the moisture content is less than 10%, and then mixed with sodium silicate in a mechanical stirrer. Water is then added and mixed for 15 minutes for hydration reaction. Then, a granulator is used to make particles with a diameter of 2 mm and a length of 2 mm. The particles obtained by granulation are covered with plastic cloth and aged at 20°C for 12 hours. Then, the particles are placed in a muffle furnace with a preheating temperature of 250°C and continue to be heated to 350°C and a roasting time of 0.8 hours is started. After the roasting is completed, the particles are naturally cooled to obtain composite mineral particles; the particle size of the bentonite and carbide slag is independently ≤74μm; the mass ratio of the bentonite and carbide slag is 20:80; the mass of the sodium silicate accounts for 1.3% of the mass of the bentonite, carbide slag and 6wt.% of the total mass of sodium silicate; the mass ratio of the total mass of the bentonite, carbide slag and sodium silicate to water is 1:0.8; the chemical composition of the bentonite is as follows by mass percentage: SiO2: 74.64%, Al2O3: 14.56%, Na2O: 3.61%, CaO: 1.83%, MgO: 3.15%, Fe2O3: 1.63%, K2O: 0.43%, others: 0.15%; the chemical composition of the carbide slag is as follows by mass percentage: CaO: 90.34%, SiO2: 5.43%, Al2O3: 2.90%, Fe2O3: 0.21%, MgO: 0.15%, impurities: 0.97%.

[0121] Comparative Example 1

[0122] The difference from Example 1 is that undried carbide slag is used and the moisture content is controlled at 50-70%. The rest of the content is consistent with Example 1.

[0123] Compared with Example 1, the use of carbide slag with a high moisture content results in the heat released by the carbide slag in the initial stage not being utilized, which is not conducive to the hydration reaction with bentonite to form hydrated calcium silicate (CSH) gel, etc.

[0124] Comparative Example 2

[0125] The difference from Example 1 is that bentonite, carbide slag and sodium carbonate are mechanically mixed and uniformly prepared into mixture A; mixture A is extruded and crushed to prepare mixed particles B, and mixed particles B are directly roasted without aging. The rest of the contents are consistent with Example 1.

[0126] Compared with Example 1, the crushing effect easily causes the mixed particles B to become loose and cracked, affecting the cohesiveness of the particles and preventing them from being well formed. In addition, the prepared mixed particles B are not aged, the hydration reaction is insufficient, and calcium silicate hydrate (CSH) gel cannot be well formed, which is not conducive to particle cohesion.

[0127] Comparative Example 3

[0128] The difference from Example 1 is that no preheating is performed before calcination, and the rest of the contents are the same as Example 1.

[0129] The present invention uses preheating to avoid cracking of particles caused by too high a temperature at the start of calcination. After aging, the large amount of calcium silicate hydrate (CSH) gel formed by the particles is dehydrated and condensed after preheating and calcination to form a large amount of amorphous tricalcium silicate 3CaO·SiO2 or dicalcium silicate 2CaO·SiO2, which is tightly and firmly combined with Ca(OH)2. This ensures that the particles will not be lost during subsequent wastewater treatment, and OH - The ions are released slowly.

[0130] Comparative Example 4

[0131] The difference from Example 1 is that undried carbide slag is used, and the moisture content is controlled at 50-70%, and bentonite, carbide slag and sodium carbonate are mechanically mixed and uniformly prepared into mixture A; the mixture A is extruded and crushed to prepare mixed particles B, and the mixed particles B are directly roasted without aging and preheating. The rest of the contents are consistent with Example 1.

[0132] Compared with Example 1, the use of carbide slag with a high moisture content results in the heat released in the initial stage of the carbide slag not being utilized, which is not conducive to the hydration reaction with bentonite to form a large amount of hydrated calcium silicate (CSH) gel, etc.; the crushing effect easily causes the interior of the mixed particles B to become loose and cracked, affecting the cohesiveness of the particles and preventing them from being well formed. Moreover, the prepared mixed particles B are directly roasted without aging and preheating, resulting in insufficient hydration reaction and failure to well form a large amount of hydrated calcium silicate (CSH) gel, etc., which is not conducive to particle bonding; because the amount of hydrated calcium silicate (CSH) gel formed by the particles after aging is small, after preheating and roasting, dehydration condensation only forms a small amount of amorphous tricalcium silicate 3CaO·SiO2 or dicalcium silicate 2CaO·SiO2, which cannot be tightly and firmly combined with Ca(OH)2, etc., so that the composite particles are easily worn and lost during subsequent wastewater treatment, and are basically in a broken particle state. - The ion release rate is too fast, resulting in the direct generation of Mn(OH)2 precipitation in the water sample, and the synergistic effect of adsorption-surface precipitation-contact self-catalytic oxidation-aggregation self-growth cannot occur, and the manganese oxides cannot be recovered and produced.

[0133] Application Example 1

[0134] Mn in acidic manganese-containing wastewater 2+ The method for preparing manganese oxides by mineralization recovery comprises the following steps:

[0135] 0.1 g of the composite mineral particles prepared in Example 1 were mixed with 1 L of a solution having an initial pH of 3.2 and heavy metal Mn 2+Acidic wastewater with a concentration of 100 mg / L was mixed, of which 1L of acidic manganese-containing wastewater was intermittently added in 5 times, 200mL each time, with an interval of 1 hour between each addition of water. The wastewater was controlled to undergo hydration reaction under stirring conditions at a speed of 120 r / min, and the composite mineral particles continuously released OH - Its surface is negatively charged to adsorb Mn in the acidic manganese-containing wastewater 2+ The surface precipitation of Mn(OH)2 is formed, and the surface is subjected to autocatalytic oxidation in contact with dissolved oxygen in water, and then the surface is subjected to the synergistic effect of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation and self-growth, resulting in the remaining composite mineral particles with a thin shell-like manganese oxide (mainly containing Mn3O4 and MnO2) on the surface.

[0136] After obtaining the remaining composite mineral particles with thin shell-like manganese oxides (mainly containing Mn3O4 and MnO2) on their surfaces, the purified water sample is discharged, and the remaining composite mineral particles with thin shell-like manganese oxides (mainly containing Mn3O4 and MnO2) on their surfaces are collected and naturally dried for 48 hours. The thin shell-like manganese oxides are then separated from the remaining composite mineral particles using an oscillator in the art. The detached thin shell-like manganese oxides and the remaining composite mineral particles are removed and recovered separately. The recovered thin shell-like manganese oxides (mainly containing Mn3O4 and MnO2) are used as manganese battery materials, photocatalysts, raw materials for manganese oxides, raw materials for electrolytic manganese, and raw materials for smelting heavy metals or pigments. The recovered particles are used as adsorbents. After saturation with heavy metal ions, the recovered remaining composite mineral particles can continue to be recycled as metal mineral resources, achieving a waste-free, green, and circular economy.

[0137] The present invention provides Mn in acidic manganese-containing wastewater 2+ The method of preparing manganese oxides by mineralization recovery is used to prepare manganese oxides (mainly containing Mn3O4, MnO2), Mn 2+ The mineralization recovery amount reaches 400mg / g, the manganese content in manganese oxides reaches more than 42.65wt.%, and the valuable metal Mn 2+ Mineralization fixation recovery effect is good.

[0138] Application Example 2

[0139] Mn in acidic manganese-containing wastewater 2+ The method for preparing manganese oxides by mineralization recovery comprises the following steps:

[0140] 0.4 g of the composite mineral particles prepared in Example 2 were mixed with 1 L of a solution having an initial pH of 3.2 and heavy metal Mn 2+Acidic wastewater with a concentration of 500 mg / L was mixed, of which 1L of acidic manganese-containing wastewater was intermittently added in 5 times, 200mL each time, with an interval of 1 hour between each addition of water. The wastewater was controlled to undergo hydration reaction under stirring conditions at a speed of 150 r / min, and the composite mineral particles continuously released OH - Its surface is negatively charged to adsorb Mn in the acidic manganese-containing wastewater 2+ The surface precipitation of Mn(OH)2 is formed, and the surface is subjected to autocatalytic oxidation in contact with dissolved oxygen in water, and then the surface is subjected to the synergistic effect of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation and self-growth, resulting in the remaining composite mineral particles with a thin shell-like manganese oxide (mainly containing Mn3O4 and MnO2) on the surface.

[0141] After obtaining the remaining composite mineral particles with thin shell-like manganese oxides (primarily containing Mn3O4 and MnO2) on their surfaces, the purified water sample is discharged, and the remaining composite mineral particles with thin shell-like manganese oxides (primarily containing Mn3O4 and MnO2) on their surfaces are collected and naturally dried for 48 hours. The thin shell-like manganese oxides are then separated from the remaining composite mineral particles using an oscillator. The detached thin shell-like manganese oxides and the remaining composite mineral particles are then removed and recycled for separate applications. The recovered thin shell-like manganese oxides (primarily containing Mn3O4 and MnO2) are used as manganese battery materials, photocatalysts, raw materials for manganese oxides, raw materials for electrolytic manganese, and raw materials for smelting heavy metals or pigments. The recovered remaining composite mineral particles are used as adsorbents. After saturating the recovered remaining composite mineral particles with heavy metal ions, they can be further recycled as a metal mineral resource, achieving a waste-free, green, and circular economy.

[0142] The present invention provides Mn in acidic manganese-containing wastewater 2+ The method of mineralization recovery to produce manganese oxides produced manganese oxides (mainly containing Mn3O4, MnO2), Mn 2+ The mineralization recovery amount reaches 480mg / g, the manganese content in manganese oxides reaches more than 65.62wt.%, and the valuable metal Mn 2+ Mineralization fixation recovery effect is good.

[0143] Application Example 3

[0144] Mn in acidic manganese-containing wastewater 2+ The method for preparing manganese oxides by mineralization recovery comprises the following steps:

[0145] 0.48 g of the composite mineral particles prepared in Example 3 were mixed with 1 L of a solution having an initial pH of 3.0 and heavy metal Mn 2+Acidic wastewater with a concentration of 700 mg / L was mixed, of which 1L of acidic manganese-containing wastewater was intermittently added in 4 times, 250mL each time, with an interval of 1 hour between each addition of water. The wastewater was controlled to undergo the first hydration reaction under stirring conditions at a speed of 150 r / min, and the composite mineral particles continuously released OH - Its surface is negatively charged to adsorb Mn in the acidic manganese-containing wastewater 2+ The surface precipitation of Mn(OH)2 is formed, and the surface is subjected to autocatalytic oxidation in contact with dissolved oxygen in water, and then the surface is subjected to the synergistic effect of adsorption-surface precipitation-contact autocatalytic oxidation-aggregation and self-growth, resulting in the remaining composite mineral particles with a thin shell-like manganese oxide (mainly containing Mn3O4 and MnO2) on the surface.

[0146] After obtaining the remaining composite mineral particles with thin shell-like manganese oxides (primarily containing Mn3O4 and MnO2) on their surfaces, the purified water sample is discharged, and the remaining composite mineral particles with thin shell-like manganese oxides (primarily containing Mn3O4 and MnO2) on their surfaces are collected and naturally dried for 48 hours. The thin shell-like manganese oxides are then separated from the remaining composite mineral particles using an oscillator. The detached thin shell-like manganese oxides and the remaining composite mineral particles are then removed and recovered separately. The recovered thin shell-like manganese oxides (primarily containing Mn3O4 and MnO2) are used as manganese battery materials, photocatalysts, raw materials for manganese oxides, raw materials for electrolytic manganese, and raw materials for heavy metal smelting or pigments. The recovered remaining composite mineral particles are used as adsorbents. After saturating the recovered remaining composite mineral particles with heavy metal ions, they can be further recycled as a metal mineral resource, achieving a waste-free, green, and circular economy.

[0147] The present invention provides Mn in acidic manganese-containing wastewater 2+ The method of mineralization recovery to produce manganese oxides produced manganese oxides (mainly containing Mn3O4, MnO2), Mn 2+ The mineralization recovery amount reaches 570mg / g, the manganese content in manganese oxides reaches more than 76.00wt.%, and the valuable metal Mn 2+ Mineralization fixation recovery effect is good.

[0148] Application Example 4

[0149] Mn in acidic manganese-containing wastewater 2+ The method for preparing manganese oxides by mineralization recovery comprises the following steps:

[0150] 1.0 g of the composite mineral particles prepared in Example 4 were mixed with 1 L of a solution having an initial pH of 3.2 and heavy metal Mn 2+Acidic wastewater with a concentration of 100 mg / L was mixed, of which 1L of acidic manganese-containing wastewater was intermittently added in 5 times, 200mL each time, with an interval of 1 hour between each addition of water. The wastewater was controlled to undergo hydration reaction under stirring conditions at a speed of 150 r / min, and the composite mineral particles continuously released OH - Its surface is negatively charged to adsorb Mn in the acidic manganese-containing wastewater 2+ Mn(OH)2 surface precipitation is formed. Due to the large amount of composite mineral particles, more Ca(OH)2 is released to neutralize H in the acidic manganese-containing wastewater. + , and excess OH - Diffusion into the water sample and Mn 2+ The Mn(OH)2 precipitate formed in the water sample continuously contacts and collides with the Mn(OH)2 precipitate formed on the particle surface, undergoes self-catalytic oxidation, aggregation and self-growth, and coagulation, which can better remove the Mn in the wastewater. 2+ Mineralization recovery yielded precipitated manganese oxides (mainly containing Mn3O4 and MnO2) and remaining composite mineral particles;

[0151] After obtaining the precipitated manganese oxides (primarily containing Mn3O4 and MnO2) and remaining composite mineral particles, the purified water sample is discharged, and the precipitated manganese oxides (primarily containing Mn3O4 and MnO2) and remaining composite mineral particles are collected and dried in a 105°C oven for 3 hours. The manganese oxides and remaining composite mineral particles are removed and recovered separately. The recovered precipitated manganese oxides (primarily containing Mn3O4 and MnO2) are used as materials for manganese batteries, photocatalysts, raw materials for manganese oxides, raw materials for electrolytic manganese, raw materials for heavy metal smelting, or pigments. The recovered remaining composite mineral particles are used as adsorbents. After saturation with heavy metal ions, the recovered remaining composite mineral particles can be further recycled as a metal mineral resource, achieving a waste-free, green, and circular economy.

[0152] The present invention provides Mn in acidic manganese-containing wastewater 2+ The method of mineralization recovery to produce manganese oxides produced manganese oxides (mainly containing Mn3O4, MnO2), Mn 2+ The mineralization recovery amount reaches 100mg / g, the manganese content in manganese oxides reaches more than 57.79wt.%, and the valuable metal Mn 2+ The mineralization fixation recovery effect is good. The pH of the effluent can reach 8.3, and the heavy metal removal rate reaches 100%, which can meet the discharge standards.

[0153] Comparative Application Example 1

[0154] The difference from Application Example 1 is that the composite mineral particles prepared in Example 1 are replaced by the composite mineral particles prepared in Comparative Example 4, and the rest of the contents are consistent with Application Example 1.

[0155] When the composite mineral particles prepared in Comparative Example 4 were used to treat wastewater at a certain rotation speed of 120 r / min, they were worn and lost, and were basically in a state of broken particles, and could not be recovered to prepare manganese oxides.

[0156] Performance Testing

[0157] Figure 2 is a photograph of the raw material bentonite of the present invention, Figure 3 is a photograph of the raw material carbide slag of the present invention, and Figure 4 is a photograph of the composite mineral particles prepared in Example 3 of the present invention. It can be seen from Figures 2 and 3 that both the bentonite and the carbide slag are powdery and fine particles, and it can be seen from Figure 4 that the prepared composite mineral particles are uniform in size and are not easy to loosen.

[0158] Figure 5 shows the composite mineral particles obtained in Example 1 of the present invention for treating acidic Mn-containing 2+ The SEM image of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after the wastewater treatment, Figure 6 is the composite mineral particles obtained in Example 1 of the present invention to treat acidic Mn-containing 2+ The EDS images of the residual composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment. As can be seen from Figures 5 and 6, nano-granular manganese oxides (mainly containing Mn3O4 and MnO2) are finally formed on the surface of the composite mineral particles. The Mn content is above 42.65wt.%, and the valuable metal Mn 2+ Mineralization fixation and recovery of manganese oxides are effective.

[0159] FIG7 shows the composite mineral particles obtained in Example 2 of the present invention for treating acidic Mn-containing 2+ The SEM image of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after the wastewater treatment, Figure 8 is the composite mineral particles obtained in Example 2 of the present invention to treat acidic Mn-containing 2+ The EDS graph of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after the wastewater treatment. Figure 9 is the EDS graph of the composite mineral particles obtained in Example 2 of the present invention for treating acidic Mn-containing 2+ The XRD patterns of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment are shown in Figures 7 to 9. It can be seen that rose petal-shaped manganese oxides (mainly containing MnO2 and Mn3O4) are finally formed on the surface of the composite mineral particles. The Mn content is above 65.62wt.%, and the valuable metal Mn 2+ Mineralization fixation recovery effect is good.

[0160] FIG10 is a graph showing the composite mineral particles prepared in Example 3 of the present invention for treating acidic Mn-containing 2+ Figure 11 is a SEM image of the composite mineral particles prepared in Example 3 of the present invention, and Figure 12 is a SEM image of the composite mineral particles prepared in Example 3 of the present invention after treatment of acidic Mn-containing 2+Figure 13 is an EDS image of the composite mineral particles prepared in Example 3 of the present invention, and Figure 14 is an EDS image of the composite mineral particles prepared in Example 3 of the present invention after treating acidic Mn-containing 2+ The EDS graph of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after the wastewater treatment, FIG15 is the composite mineral particles prepared in Example 3 of the present invention to treat acidic Mn-containing 2+ The XPS full spectrum comparison chart before and after the wastewater treatment is shown in Figure 16. The composite mineral particles prepared in Example 3 of the present invention treat acidic Mn-containing 2+ The XPS O 1s high-resolution spectrum of the remaining composite mineral particles with thin shell-like manganese oxides on the surface generated after the wastewater treatment. Figure 17 shows the composite mineral particles prepared in Example 3 of the present invention for treating acidic Mn-containing 2+ The XPS Mn 2p high-resolution spectrum of the residual composite mineral particles with thin shell-like manganese oxides on the surface generated after wastewater treatment. As can be seen from Figures 10 to 17, the prepared composite mineral particles are not easy to loosen after the reaction, and dark brown Mn3O4 and MnO2 are generated on the particle surface. The composite mineral particles treat acidic Mn-containing 2+ The wastewater before treatment is porous layered structure and does not contain Mn element. Composite mineral particles can treat acidic Mn-containing wastewater. 2+ The nano-granular and nano-rod-shaped manganese oxides Mn3O4 and MnO2 generated after the wastewater are covered on the surface of the remaining composite mineral particles. The Mn content is above 76.00wt.%, and the XPS Mn 2p high-resolution spectrum further shows that Mn(Ⅲ) and Mn(Ⅳ) Mn3O4 and MnO2 are generated. The valuable metal Mn 2+ Mineralization fixation and recovery of manganese oxides are effective.

[0161] FIG18 is a graph showing the composite mineral particles prepared in Example 4 of the present invention for treating acidic Mn-containing 2+ Figure 19 is the effect diagram of the coprecipitation of manganese oxides generated after wastewater treatment. Figure 19 is the effect diagram of the composite mineral particles prepared in Example 4 of the present invention for treating acidic Mn-containing 2+ SEM image of the coprecipitated manganese oxides generated after wastewater treatment. Figure 20 is the SEM image of the composite mineral particles prepared in Example 4 of the present invention for treating acidic Mn-containing 2+ EDS diagrams of the precipitated manganese oxides generated after wastewater treatment. As shown in Figures 18 to 20, the precipitated manganese oxides are relatively large and easy to separate from mud and water. The generated black-brown granular Mn3O4 and MnO2 aggregate and grow into large granular structures. The Mn content reaches more than 57.79wt.%, and the valuable metal Mn 2+ Mineralization fixation and recovery of manganese oxides are effective.

[0162] FIG21 is an XRD diagram of the composite mineral particles before and after calcination in Example 3 of the present invention, wherein 1-Ca(OH)2, 2-CaCO3, 3-CSH, 4-MMT, 5-Na2(CaCO3)2·5H2O. As shown in FIG21, the main components of the composite mineral particles before calcination include Ca(OH)2, 2-CaCO3, 3-CSH, 4-MMT, and 5-Na2(CaCO3)2·5H2O. 2 , CaCO3, and calcium silicate (calcium silicate hydrate (CSH)) are dehydrated and condensed to form amorphous calcium silicate 3CaO·SiO2 or 2CaO·SiO2 after calcination.

[0163] FIG22 is a graph showing the composite mineral particles prepared in Comparative Example 4 of the present invention, which are processed at a rotation speed of 120 r / min to contain Mn. 2+ As shown in FIG22 , the composite mineral particles prepared in Comparative Example 4 were worn and lost under certain rotation speed conditions, and were basically in a broken particle state, and could not be recovered to prepare manganese oxides.

[0164] The present invention provides Mn in acidic manganese-containing wastewater 2+ The method of mineralization recovery to prepare manganese oxides has an initial pH value of 2 to 6 and heavy metal Mn 2+ By treating acidic manganese-containing wastewater with a concentration of 10 to 700 mg / L, high-purity manganese oxides (mainly containing Mn3O4, MnO2) can be produced. 2+ The mineralization recovery amount reaches 100-600 mg / g, the manganese content in manganese oxides reaches more than 40-76%, and the valuable metal Mn 2+ Mineralization and fixation are effective in recovering manganese oxides. When the composite mineral particle dosage is 1.0-2.0g / L, the effluent pH can reach 6-9, and the heavy metal removal rate reaches 95-100%, allowing discharge standards to be met. This also enables resource utilization of industrial solid waste calcium carbide slag, transforming waste into treasure, treating waste with waste, and simultaneously treating wastewater and waste residue, promoting a circular economy.

[0165] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A composite mineral particle, characterized in that: The preparation material is prepared by hydration reaction and roasting dehydration condensation of raw materials, and the raw materials include bentonite, carbide slag and an activator.

2. The composite mineral particles according to claim 1, characterized in that The activator includes sodium carbonate and / or sodium silicate.

3. The composite mineral particles according to claim 1, characterized in that The bentonite is sodium bentonite.

4. The composite mineral particles according to claim 1 or 3, characterized in that: The chemical components of the bentonite include, by mass percentage, SiO2: 65-80%, Al2O3: 11-17%, Na2O: 3.0-6.0%, CaO: 1.5-3.5%, MgO: 2.0-5.0%, Fe2O3: 1.6-4.0%, K2O: 0.1-1.2%, and impurities: 0.1-2.16%.

5. The composite mineral particles according to claim 1, characterized in that The chemical composition of the carbide slag includes, by mass percentage, CaO: 86.7-94.5%, SiO2: 2.0-6.5%, Al2O3: 0.5-3.0%, Fe2O3: 0.2-1.5%, MgO: 0.10-0.22%, and impurities: 0.8-2.32%.

6. The composite mineral particles according to claim 1, 3 or 5, characterized in that: The particle sizes of the bentonite and carbide slag are independently ≤74 μm; the mass ratio of the bentonite and carbide slag is (20-50):(50-80).

7. The composite mineral particles according to claim 1, 2, 3 or 5, characterized in that: The mass of the activator is 5-9% of the total mass of the bentonite, carbide slag and the activator.

8. The method for preparing the composite mineral particles according to any one of claims 1 to 7, comprising the following steps: Carbide slag and an activator are subjected to a first hydration reaction in water to obtain a first hydration reaction product; The first hydration reaction product is sequentially granulated, aged and calcined for dehydration and condensation to obtain composite mineral particles.

9. The preparation method according to claim 8, characterized in that: Before the first hydration reaction, the bentonite and carbide slag are dried; the drying temperature is 100-110° C.; the drying time is 2-4 hours; and the drying is performed until the moisture content of the bentonite and carbide slag is less than 10%.

10. The preparation method according to claim 8, characterized in that: The mass ratio of the total mass of the bentonite, carbide slag and activator to water is 1:(0.6-0.9).

11. The preparation method according to claim 8, characterized in that: The granulation is wet granulation; the particle size of the granules obtained by the granulation is 1 to 4 mm.

12. The preparation method according to claim 8, characterized in that: The aging temperature is 10-35° C. and the aging time is 6-24 hours.

13. The preparation method according to claim 8, characterized in that: Before the roasting dehydration condensation is performed, the method further includes: preheating the particles obtained by aging; the preheating temperature is 250° C., and the heat preservation time is 10 minutes.

14. The preparation method according to claim 8, characterized in that: The temperature of the roasting dehydration condensation is 300-500° C., and the heat preservation time is 0.5-1.5 h.

15. Use of the composite mineral particles according to any one of claims 1 to 7 or the composite mineral particles prepared by the preparation method according to any one of claims 8 to 14 in treating acidic manganese-containing wastewater.

16. A method for treating acidic manganese-containing wastewater to recover manganese oxides, characterized in that: The following steps are involved: The acidic manganese-containing wastewater is intermittently mixed with the composite mineral particles to carry out a second hydration reaction, and the obtained second hydration reaction product carries out a synergistic action of adsorption-surface precipitation-contact self-catalytic oxidation-aggregation self-growth on the manganese ions in the acidic manganese-containing wastewater to obtain manganese oxides and remaining composite mineral particles; The intermittent addition is to add the acidic manganese-containing wastewater intermittently 3 to 7 times, and the interval between each two adjacent additions is 1 hour; The composite mineral particles are the composite mineral particles according to any one of claims 1 to 7 or the composite mineral particles prepared by the preparation method according to any one of claims 8 to 14.

17. The method according to claim 16, characterized in that The pH value of the acidic manganese-containing wastewater is 2-6; the concentration of divalent manganese ions in the acidic manganese-containing wastewater is 10-700 mg / L; the amount of the composite mineral particles added per liter of the acidic manganese-containing wastewater is 0.01-0.5 g or 1-2 g.

18. The method according to claim 16, characterized in that Also includes: The manganese oxide is recycled as a raw material or finished product; and the remaining composite mineral particles are recycled as an adsorbent.

19. The method according to claim 18, characterized in that The adsorbent is used to adsorb low-concentration heavy metal ion wastewater; the heavy metal ions in the low-concentration heavy metal ion wastewater are Fe 2+ , Mn 2+ , Cu 2+ 、Zn 2+ , Hg 2+ 、Cd 2+ , Pb 2+ Cr 3+ and Ni 2+ One or more of the following; the concentration of heavy metal ions in the low-concentration heavy metal ion wastewater is 0.1 to 10 mg / L.

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