CN114162796A - Method for recycling and regenerating phosphate waste - Google Patents

Abstract

The invention discloses a method for recycling and regenerating phosphate waste, which comprises the following steps: the powder containing the phosphate waste and a reducing agent are subjected to a dissolution reaction in an acid solution, so that metal elements and phosphate radicals contained in the phosphate waste are leached out; carrying out solid-liquid separation to remove insoluble substances; adding an oxidant to carry out oxidation reaction on the leached metal element and phosphate radical to obtain a regenerated phosphate crude product; cleaning, drying and screening the regenerated phosphate crude product to obtain a regenerated phosphate finished product; separating phosphate to obtain regenerated mother liquor, and preparing the manganese regenerated product by a precipitation method. The reducing agent and the oxidizing agent adopted by the invention have high reaction activity, are green and environment-friendly, and have simple process conditions and low cost; the oxidant is regenerated while the regenerated phosphate is recovered, and the oxidant can be recycled. The invention is particularly suitable for recycling and regenerating manganese phosphate or manganese ferric phosphate.

Description

Method for recycling and regenerating phosphate waste

Technical Field

The invention relates to the technical field of lithium ion battery recovery, in particular to a method for recovering and regenerating phosphate waste materials of raw materials of a lithium ion battery.

Background

In 2020, the subsidy policy in China moves away from the slope and the requirement on the energy density of a battery system is not increased any more, so that the subsidy acquisition difference between the lithium iron vehicle type and the ternary vehicle type is reduced to a certain extent. The cost performance advantage of the lithium iron battery begins to be embodied. In addition, the improvement of the battery and the whole vehicle technology, and a plurality of high-quality pure electric vehicle types using the lithium iron are released. The lithium iron vehicle type becomes an explosion type vehicle type, and the lithium iron battery returns to the mainstream visual field of the passenger vehicle. In addition, the construction of the 5G base station is accelerated, the market growth of foreign storage is promoted, the market segments such as small power, heavy trucks and engineering machinery are driven, and the delivery amount of the lithium iron phosphate anode material is greatly increased. According to prediction, the shipment of the lithium iron phosphate material in 2025 is expected to break through millions of tons. With the progress of material technology, the lithium iron manganese phosphate material is also commercialized due to a higher voltage platform and better low-temperature performance, and is expected to be applied in a large scale in the future. The back of the dramatic increase in the quantity of products and the application of a large amount of products means that huge quantities of lithium iron phosphate/lithium iron manganese phosphate batteries are decommissioned every year in the future, and huge quantities of lithium iron phosphate waste materials, lithium iron manganese phosphate waste materials, iron phosphate waste materials and ferric manganese phosphate waste materials are to be recycled and regenerated.

In the recovery process of the waste lithium iron phosphate/ferromanganese phosphate lithium battery, high-value lithium is generally recovered firstly, and the remaining waste ferric phosphate/ferromanganese phosphate residue contains a high-molecular binder and conductive carbon, and usually also contains impurities such as aluminum, copper and the like, and contains a certain amount of negative electrode graphite powder. From the viewpoint of the overall management of manganese, iron and phosphorus resources and the environmental protection, the phosphate waste residues must be properly treated.

Chinese patent (CN 109095481A) discloses a comprehensive recovery method of waste lithium iron phosphate powder, which comprises the steps of oxidizing and roasting the waste powder to obtain activated calcine, then respectively obtaining lithium-containing mother liquor and iron phosphate filter residues by a reverse acid leaching method, and finally obtaining battery-grade lithium carbonate by the processes of removing impurities and weight, precipitating lithium, washing lithium and the like. Although the method realizes the recycling of lithium element, the quality problem of the ferric phosphate caused by incomplete oxidation is not solved. In addition, in the filter residue, the ferric phosphate, the high molecular binder and the nano conductive carbon are mixed together, and the method does not provide a reasonable separation process and a purification process of the ferric phosphate. Chinese patent (CN 108899601 a) discloses a method for removing organic substances and carbon in iron phosphate filter residue by calcination. However, the high molecular binder decomposes at high temperature to generate harmful gases, which easily causes equipment corrosion and has high requirements for tail gas purification treatment. At present, because the value of lithium is high and the values of phosphorus, iron and the like are low, a recycling manufacturer generally treats mixed slag of iron phosphate, a binder and carbon as waste slag after recycling lithium, and does not implement recycling. The iron phosphate and the conductive carbon are nano-scale materials and are mixed with a binder, so that the mixture is extremely viscous and difficult to separate. Patent CN 112320780A provides a method for recovering iron phosphate waste, in which the iron phosphate waste is leached in an acidic solution, and then ferrous ions are oxidized by using hydrogen peroxide as an oxidizing agent to form ferric orthophosphate which is precipitated. The hydrogen peroxide is a strong oxidizing and corrosive acidic liquid and is a dangerous product, and the hydrogen peroxide is used as a main raw material to increase the equipment investment and management cost of a recycling plant. Moreover, the price of hydrogen peroxide is high, so that the economic efficiency of iron phosphate recovery and regeneration is not superior.

Disclosure of Invention

The present invention provides a method for recovering and regenerating phosphate waste to solve the above problems. The method provided by the invention uses safe and efficient reducing agent and oxidant, and has high reaction activity, safety and controllability; secondly, the oxidant is renewable and can be recycled; thirdly, in the whole process of recovery and regeneration, the reduction leaching is carried out firstly, then the oxidation precipitation is carried out, the phosphate is purified, and the phosphate is separated from the binder and the carbon.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a method for recovering and regenerating phosphate waste materials comprises the following steps:

step 1, carrying out a dissolution reaction on powder containing phosphate wastes and a reducing agent in an acid solution to leach out metal elements and phosphate radicals contained in the phosphate wastes;

step 2, carrying out solid-liquid separation to remove insoluble substances;

step 3, adding an oxidant to carry out oxidation reaction on the leached metal element and phosphate radical to obtain a regenerated phosphate crude product;

step 4, cleaning, drying and screening the regenerated phosphate crude product to obtain a regenerated phosphate finished product;

wherein the reducing agent is selected from iron powder and at least one polyol; the oxidant is at least one of manganese dioxide, pyrolusite and manganous-manganic oxide.

The phosphate contained in the phosphate waste has the general formula MPO₄Wherein the element M is at least one of metal elements Fe, Co, Ni, Mn and V. The phosphate contained in the phosphate waste comprises any one or more of the following materials: FePO₄、MnPO₄、Fe_yMn_1-yPO₄（0<y<1）、CoPO₄、Fe_yCo_1-yPO₄（0<y<1）、NiPO₄、Fe_yNi_1-yPO₄（0<y<1) And VPO₄. Said phosphate is preferably Fe_yMn_1-yPO₄（0<y<1) E.g. Fe_0.4Mn_0.6PO₄。

The acid solution is any one or more of sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid solution.

The reducing agent is at least one selected from iron powder and polyhydric alcohol, and the reducing agent can also be aldehyde. The polyalcohol is any one or more of ethylene glycol, glycerol and 1, 2-propylene glycol. The aldehyde is selected from formaldehyde and acetaldehyde.

As a preferable scheme, when the powder containing the phosphate waste and the reducing agent are subjected to dissolution reaction in an acidic solution, a surfactant is added, and the molecular structure of the surfactant is as follows:

in the formula, substituent groups R1, R2, R3 and R4 are hydrogen or alkyl with 1-18 carbon atoms.

The surfactant is selected from any one or more of octyl trimethyl ammonium sulfate, decyl trimethyl ammonium sulfate, dodecyl trimethyl ammonium sulfate and hexadecyl trimethyl ammonium sulfate. The addition amount of the surfactant is 0.5-5% of the mass of the orthophosphate waste. When the reducing agent is a polyol, the polyol may serve as a surfactant, and the quaternary ammonium salt catalyst described above may not be added.

When the phosphate waste and the reducing agent are reacted in an acid solution, the reducing agent is excessive by 0.5-5% according to the stoichiometric amount. The reaction temperature is 0-120 ℃, and the reaction time is 0.1-24 hours. Preferably, the reaction temperature is 60-100 ℃ and the reaction time is 2-12 hours.

When the oxidant is added to lead the transition metal element and the phosphate radical to generate phosphate, the oxidant is reduced by 0.2 to 2 percent according to the stoichiometric amount. The reaction temperature is 0-120 ℃, and the reaction time is 0.1-24 hours. Preferably, the reaction temperature is 60-100 ℃ and the reaction time is 2-12 hours.

Preferably, the method for recycling and regenerating phosphate waste further comprises the following steps:

step 21 is included between step 2 and step 3: adjusting the pH value, and removing impurities;

step 4 is followed by step 5: separating phosphate to obtain a regeneration mother liquor, removing impurities, adjusting the pH value of the regeneration mother liquor, and preparing a manganese regeneration product by a precipitation method, wherein the manganese regeneration product is manganese hydroxide or manganese oxide.

In the step 5, the oxide of manganese is preferably trimanganese tetroxide.

Compared with the prior art, the method for recovering and regenerating the phosphate, provided by the invention, comprises the steps of separating the phosphate from the binder and the conductive carbon through reduction leaching, and then adding the oxidant to enable iron and/or manganese and phosphate radical to generate the phosphate, so that the phosphate is purified and regenerated. The high-valence manganese compound is used as an oxidant, and the oxidant can be recycled, so that the cost is reduced.

Drawings

FIG. 1 is a flow diagram of a process for the recovery and regeneration of phosphate waste in accordance with the present invention;

FIG. 2 is another flow diagram of a method for recycling and regenerating phosphate waste in accordance with the present invention.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments shown in the drawings. These embodiments are not intended to limit the present invention, and structural, methodological, or functional changes made by those skilled in the art according to these embodiments are included in the scope of the present invention.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

In the recovery process of the waste lithium iron phosphate/ferromanganese phosphate lithium battery, high-value lithium is generally recovered firstly, and the remaining waste ferric phosphate/ferromanganese phosphate residue contains a high-molecular binder and conductive carbon, and usually also contains impurities such as aluminum, copper and the like, and contains a certain amount of negative electrode graphite powder.

The invention provides a method for recycling and regenerating phosphate waste, which comprises the following steps as shown in figure 1:

step 1, carrying out a dissolution reaction on powder containing phosphate wastes and a reducing agent in an acid solution to leach out metal elements and phosphate radicals contained in the phosphate wastes;

step 2, carrying out solid-liquid separation to remove insoluble substances;

step 3, adding an oxidant to carry out oxidation reaction on the leached metal element and phosphate radical to obtain a regenerated phosphate crude product;

and 4, cleaning, drying and screening the regenerated phosphate crude product to obtain a regenerated phosphate finished product.

Wherein the reducing agent is selected from at least one of iron powder and polyhydric alcohol; the oxidant is at least one of manganese dioxide, pyrolusite and manganous-manganic oxide.

In step 1, the phosphate contained in the phosphate waste has the general formula MPO₄Wherein the element M is at least one of metal elements Fe, Co, Ni, Mn and V. The phosphate contained in the phosphate waste comprises any one or more of the following materials: FePO₄、MnPO₄、Fe_yMn_1-yPO₄（0<y<1）、CoPO₄、Fe_yCo_1-yPO₄（0<y<1）、NiPO₄、Fe_yNi_1-yPO₄（0<y<1) And VPO₄。

The surface coating or doping modification of the anode material is a common means for improving the electrochemical performance of the material. Common coating materials are ZnO and ZrO₂、AlPO₄、Li₃PO₄、Al₂O₃、AlF₃、SiO₂、TiO₂MgO and Li, a boron-lithium compound₂O-2B₂O₃And the like, and organic polymer materials such as polyaniline. The doping element is at least one of metal elements of Na, K, Mg, Ca, Sr, Ba, Al, Ga, In, Ge, Sn, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, Mo, Cd, W, La, Ce, Nd and Sm, and the nonmetal element is F or S, etc. Therefore, the phosphate contained in the phosphate waste often also includes the above elements.

Because of the limitation of the oxidant of the invention (using the oxidant containing manganese element), the recovered and regenerated phosphate inevitably contains manganese element, so that the phosphate waste is preferably Fe_yMn_1-yPO₄（0<y<1) Particularly preferred is Fe_0.6Mn_0.4PO₄。

Since the phosphate waste contains a polymer binder, nano conductive carbon, and the like, the lithium is extracted and then becomes very viscous. In order to sufficiently leach out metal elements such as iron and/or manganese and phosphorus, the invention provides a reducing agent with high activity and safety, and a surfactant is added to play a synergistic effect.

The reduction leaching is carried out in an acidic solution containing a surfactant, preferably sulfuric acid, phosphoric acid as an acidic medium. The amount of acid used is related to the molecular formula of the phosphate waste. Generally, an excess of acid favors an increase in the leaching rate. However, neutralization of excess acid requires consumption of base and production of solid by-products such as sodium sulfate, ammonium sulfate. The amount of acid used is one of the main process parameters that must be optimized for each different waste material. The reducing agent may be at least one of iron powder, ethylene glycol, glycerin, and 1, 2-propylene glycol, or may be a mixture thereof, for example, a combination of iron powder and ethylene glycol, a combination of iron powder and glycerin, or the like. The reducing agent is selected based on environmental protection and high efficiency. When the phosphate is Fe_yMn_1-yPO₄（0<y<1) When used, the reducing agent must comprise at least one polyol.

The reduction reaction is preferably carried out in the presence of sulfuric or phosphoric acid, and the surfactant is therefore selected from any one or more of octyltrimethylammonium sulfate, decyltrimethylammonium sulfate, dodecyltrimethylammonium sulfate, hexadecyltrimethylammonium sulfate. If a commonly used surfactant is selected, such as CTAB (cetyltrimethylammonium bromide), CTAC (cetyltrimethylammonium chloride), impurities such as bromine, chlorine, etc. are introduced. The use of quaternary ammonium salt surfactants whose anion is sulfate has significant advantages. Firstly, no extra impurity is introduced, and secondly, the organic group only contains carbon, hydrogen and nitrogen elements, and can be removed in a heating decomposition mode in the subsequent material processing process, so that the material performance is not influenced. The addition amount of the surfactant is 0.5-5% of the mass of the phosphate waste. The addition of a proper amount of surfactant can promote the separation of the high molecular binder and the phosphate, thereby accelerating the reduction leaching reaction of the phosphate. The use amount is too small, and the effect is not obvious; too much amount is used, the cost is high and the performance of the material is influenced. When the phosphate waste and the reducing agent are reacted in an acid solution, the reaction temperature is 0-150 ℃, and the reaction time is 0.1-72 hours. Preferably, the reaction temperature is 60-100 ℃ and the reaction time is 2-12 hours. When the reduction leaching reaction is carried out in an acid solution containing a surfactant, the solid-to-liquid ratio is generally 10-2000 g/L, preferably 100-1000 g/L, and more preferably 200-600 g/L. Although the reaction can be accelerated by low solid-liquid ratio, which is beneficial to leaching, the water consumption is large and is insufficient; if the solid-liquid ratio is too high, the reaction may be incomplete and valuable elements cannot be completely leached.

The amount of the reducing agent used is related to the molecular formula of the phosphate waste powder and the kind of the reducing agent itself. The addition amount of the reducing agent is calculated in a stoichiometric ratio according to the reaction formula of the reducing agent and the waste cathode material. In order to ensure that the leaching reaction is carried out completely, a slight excess of reducing agent can be considered, and the excess of the reducing agent is 0.5-5% of stoichiometric excess. When the polyol is a reducing agent, the reducing agent may also act as a surfactant, and may be in large excess.

The purpose of adding the reducing agent is to allow the high-valence metal element (Fe) in the phosphate to be contained³⁺、Mn³⁺) Is reduced into low-valence metal element (Fe)²⁺、Mn²⁺) So that the phosphate is fully leached out and is separated from the adhesive and the conductive carbon under the synergistic action of the surfactant, and the problem that the phosphate is difficult to separate from the adhesive and the conductive nano material is solved. The metallic iron powder can reduce Fe³⁺To Fe²⁺The polyol may be Mn³⁺Reduction to Mn²⁺. When the phosphate is Fe_yMn_1-yPO₄（0<y<1) When used, the reducing agent must comprise at least one polyol.

In step 2, the insoluble substances mainly comprise organic substances, carbon and the like.

The invention also provides an oxidant for regenerating the phosphate waste. In step 3, any one or more of the following substances are preferred as the oxidizing agent, but not limited to the following compounds: manganese dioxide, manganese sesquioxide, manganous anhydride, manganic tetroxide, manganic anhydride, pyrolusite, manganite, manganosite, manganite, manganate and permanganate. Manganese dioxide, trimanganese tetroxide and high-grade pyrolusite are further preferably selected, the manganese dioxide, trimanganese tetroxide and pyrolusite are easy to purchase in the market and low in cost, the requirements of industrial production are met, and other impurities are not introduced into the oxide, so that the purification of subsequent products is facilitated. The advantage of using manganese-containing oxidant is that the regeneration cycle can be realized by a simple method of adjusting pH value. For example, manganomanganic oxide is taken as an oxidizing agent. And (3) carrying out solid-liquid separation after reduction leaching reaction to remove organic matters, carbon and other insoluble substances, then adding trimanganese tetroxide to enable the transition metal elements and phosphate radicals to generate phosphate, and carrying out solid-liquid separation after reaction to obtain manganese-containing mother liquor and phosphate. The chemical reaction formula of the oxidation reaction is shown as formula (1):

2Fe²⁺ + 2PO₄ ^3- + Mn₃O₄ + 8H⁺ = 2FePO₄ + 3Mn²⁺ + 4H₂O （1）

the regeneration reaction of the oxidizing agent is represented by the formula (2):

3Mn²⁺ + 4OH^- = Mn₃O₄ + 4H₂O （2）

the amount of oxidizing agent used is related to the molecular formula of the phosphate waste as well as the oxidizing agent itself. The amount of oxidant used is calculated stoichiometrically based on the equation for the reaction of oxidant with phosphate waste. Although a slight excess of the oxidizing agent may be considered in order to ensure the completion of the oxidation reaction, since the oxidizing agent is a solid, when the oxidizing agent is in excess, the excess oxidizing agent is mixed with the phosphate regenerated after oxidation to affect the purity of the phosphate, and therefore, it is preferable that the oxidizing agent is stoichiometrically reduced by 0.2% to 2%, that is, a relatively small amount of the oxidizing agent. The reaction temperature is 0-100 ℃, and the reaction time is 0.1-24 hours. Preferably, the reaction temperature is 60-90 ℃, and the reaction time is 2-8 hours. In order to ensure the purity of the regenerated phosphate, a proper amount of hydrogen peroxide can be added.

And 4, cleaning, drying, high-temperature processing, crushing and screening the regenerated phosphate crude product to obtain a phosphate finished product.

Further, the present invention adds a step of recovering oxides on the basis of the above method for recovering and regenerating phosphate waste, as shown in fig. 2, and specifically includes the following steps:

step 21 is included between step 2 and step 3: adjusting the pH value, and removing impurities;

step 4 is followed by step 5: separating phosphate to obtain a regeneration mother liquor, removing impurities, adjusting the pH value of the regeneration mother liquor, and preparing a manganese regeneration product by a precipitation method, wherein the manganese regeneration product is manganese hydroxide or manganese oxide.

In step 5, the trimanganese tetroxide compound is most easily obtained by a precipitation method. The manganous-manganic oxide can be used for preparing a high-end lithium manganate material. At present, electrolytic manganese dioxide is generally used as a precursor for preparing a lithium manganate material. The lithium manganate material is limited in application due to the short cycle life at high temperature. A large number of researches show that when manganous-manganic oxide is used for replacing electrolytic manganese dioxide to prepare the lithium manganate material, the cycle life and the high-temperature performance of the manganous-manganic oxide can be obviously prolonged. The manganous manganic oxide can also be used as an oxidant and applied to the recovery and regeneration of the olivine type anode material. The oxidant is regenerated while the regenerated anode material is recovered, and can be recycled, so that the closed-loop circulation of all metal elements in the method is realized.

The method for recovering and regenerating the phosphate waste is further described below by way of specific examples.

Example 1

500.0g of ferric phosphate (FePO) was weighed out separately₄) Adding waste and 97.5g of iron powder into a reactor, adding 5.0g of surfactant cetyl trimethyl ammonium sulfate, adding about 1L of water, starting stirring and heating a reaction container, and setting the reaction temperature to be 150 ℃; preparing a 37.5 mass percent sulfuric acid solution, slowly adding the solution into the container, and adding 1300g of the solution in total. After reacting for 2 hours, cooling. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Appropriate amounts of sulfuric acid and phosphoric acid were added to the leach solution to adjust the pH, followed by the addition of about 211.8g (about 2% less than stoichiometric) of electrolytic manganese dioxide. And starting stirring and heating the reaction container, setting the reaction temperature at 90 ℃, reacting for 24 hours, filtering, cleaning, drying, performing high-temperature treatment, crushing and screening to obtain the purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, crushing, sieving and the like to obtain the spherical manganous-manganic oxide.

Example 2

500.0g of ferric phosphate (FePO) was weighed out separately₄) Adding waste materials and 93.3g of iron powder into a reactor, preparing a sulfuric acid solution with the mass percentage of 37.5%, slowly adding the sulfuric acid solution into the container, and adding 1300g of the sulfuric acid solution in total; adding 25.0g of dodecyl trimethyl ammonium sulfate as surfactant, adding 1L of water, stirring andthe reaction vessel was heated and the reaction temperature was set at 100 ℃. After 12 hours of reaction, the reaction mixture was cooled. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Appropriate amounts of sulfuric acid and phosphoric acid were added to the leach solution to adjust the pH, followed by about 215.8g (about 0.2% less than stoichiometric) of electrolytic manganese dioxide. And starting stirring and heating the reaction container, setting the reaction temperature at 90 ℃, reacting for 24 hours, filtering, cleaning, drying, performing high-temperature treatment, crushing and screening to obtain the purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, crushing, sieving and the like to obtain the spherical manganous-manganic oxide.

Example 3

500.0g of ferric phosphate (FePO) was weighed out separately₄) Adding waste and 92.8g of iron powder into a reactor, adding 25.0g of surfactant dodecyl trimethyl ammonium sulfate, starting stirring and heating a reaction container, and setting the reaction temperature to 90 ℃; preparing a 37.5 mass percent sulfuric acid solution, slowly adding the solution into the container, and adding 1300g of the solution in total. After 72 hours of reaction, the reaction mixture was cooled. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Adding appropriate amount of sulfuric acid and phosphoric acid into the leaching solution, adjusting the pH value, and then adding 560.2g of manganous manganic oxide. And starting stirring and heating the reaction container, setting the reaction temperature at 90 ℃, reacting for 8 hours, filtering, cleaning, drying, crushing and screening to obtain the purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, high-temperature treatment, crushing, sieving and the like to obtain the spherical trimanganese tetroxide.

Example 4

500.0g of ferric phosphate (FePO) was weighed out separately₄) Adding waste and 95.0g of iron powder into a reactor, adding 2.5g of surfactant dodecyl trimethyl ammonium sulfate, adding about 2L of water, starting stirring and heating a reaction container, and setting the reaction temperature to be 120 ℃; preparing 50 percent of sulfur by massThe acid solution was slowly added to the above vessel, and 1800g in total was added. After reacting for 2 hours, cooling. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Adding a proper amount of phosphoric acid into the leaching solution, adjusting the pH value, and then adding 557.6g of manganous-manganic oxide. And starting stirring and heating the reaction container, setting the reaction temperature at 100 ℃, reacting for 4 hours, filtering, cleaning, drying, crushing and screening to obtain the purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, high-temperature treatment, crushing, sieving and the like to obtain the spherical trimanganese tetroxide.

Example 5

500.0g of ferric phosphate (FePO) was weighed out separately₄) Adding waste and 95.0g of iron powder into a reactor, adding 5.0g of surfactant decyl trimethyl ammonium sulfate, adding about 1.5L of water, starting stirring and heating a reaction container, and setting the reaction temperature to be 60 ℃; preparing 50% sulfuric acid solution, slowly adding into the container, and adding 1500g in total. After 72 hours of reaction, the reaction mixture was cooled. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Appropriate amounts of sulfuric acid and phosphoric acid were added to the leachate, the pH was adjusted, and 276.5g of pyrolusite (containing about 78% manganese dioxide) was added. And starting stirring and heating the reaction container, setting the reaction temperature at 60 ℃, reacting for 8 hours, filtering, cleaning, drying, performing high-temperature treatment, crushing and screening to obtain the purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, crushing, sieving and the like to obtain the spherical manganous-manganic oxide.

Example 6

500.0g of ferromanganese phosphate (Mn) was weighed out separately_0.6Fe_0.4PO₄) Adding waste material, iron powder 38.5g and ethylene glycol 20.0g into a reactor, adding surfactant decyl trimethyl ammonium sulfate 5.0g, adding water about 2L, stirring, heating the reaction container, and setting the reaction temperature at 95%DEG C; preparing a 37.5 mass percent sulfuric acid solution, slowly adding the solution into the container, and adding 1500g in total. After 48 hours of reaction, the reaction mixture was cooled. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Adding appropriate amount of sulfuric acid and phosphoric acid into the leachate, adjusting pH, and adding 215.5g manganese dioxide. And starting stirring and heating the reaction container, setting the reaction temperature at 90 ℃, reacting for 4 hours, filtering, cleaning, drying, performing high-temperature treatment, crushing and screening to obtain the purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, crushing, sieving and the like to obtain the spherical manganous-manganic oxide.

Example 7

500.0g of ferromanganese phosphate (Mn) was weighed out separately_0.6Fe_0.4PO₄) Adding the waste, 38.5g of iron powder and 40.0g of 1, 2-propylene glycol into a reactor, adding about 2L of water, starting stirring and heating a reaction container, and setting the reaction temperature to be 95 ℃; preparing a 37.5 mass percent sulfuric acid solution, slowly adding the solution into the container, and adding 1500g in total. After 48 hours of reaction, the reaction mixture was cooled. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Adding appropriate amount of sulfuric acid and phosphoric acid into the leachate, adjusting pH, and adding 215.5g manganese dioxide. And starting stirring and heating the reaction container, setting the reaction temperature at 90 ℃, reacting for 4 hours, filtering, cleaning, drying, performing high-temperature treatment, crushing and screening to obtain the purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, crushing, sieving and the like to obtain the spherical manganous-manganic oxide.

Example 8

500.0g of ferromanganese phosphate (Mn) was weighed out separately_0.6Fe_0.4PO₄) Adding waste, 38.5g of iron powder and 40.0g of ethylene glycol into a reactor, adding about 2L of water, starting stirring and heating a reaction container, and setting the reaction temperature to be 120 ℃; the mass percentage of the preparationA37.5% sulfuric acid solution was slowly added to the vessel to make 1500g in total. After reacting for 2 hours, cooling. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Adding proper amount of sulfuric acid and phosphoric acid into the leaching solution, adjusting the pH value, and then adding about 557.6g of mangano-manganic oxide. And starting stirring and heating the reaction container, setting the reaction temperature at 90 ℃, reacting for 4 hours, filtering, cleaning, drying, performing high-temperature treatment, crushing and screening to obtain the purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, high-temperature treatment, crushing, sieving and the like to obtain the spherical trimanganese tetroxide.

Example 9

500.0g of ferromanganese phosphate (Mn) was weighed out separately_0.6Fe_0.4PO₄) The waste material, iron powder 38.5g and ethylene glycol 40.0g are added into a reactor, water is added for about 2L, a sulfuric acid solution with the mass percentage of 37.5% is prepared, and the solution is slowly added into the container, and the total amount is 1500 g. The stirring was turned on and the reaction vessel was heated, setting the reaction temperature at 120 ℃. After reacting for 1 hour, cooling. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Appropriate amounts of sulfuric acid and phosphoric acid were added to the leachate, the pH was adjusted, and 276.5g of pyrolusite (containing about 78% manganese dioxide) was added. And starting stirring and heating the reaction container, setting the reaction temperature at 90 ℃, reacting for 4 hours, filtering, cleaning, drying, performing high-temperature treatment, crushing and screening to obtain the purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, high-temperature treatment, crushing, sieving and the like to obtain the spherical trimanganese tetroxide.

Example 10

500.0g of manganese phosphate (MnPO) was weighed out separately₄) Adding waste and 60.0g of ethylene glycol into a reactor, adding about 0.5L of water, starting stirring and heating the reaction container, and setting the reaction temperature to be 120 ℃; preparing the mixture with the mass percentage of 37.5 percentThe sulfuric acid solution was slowly added to the above vessel, and a total of 1500g was added. After reacting for 2 hours, cooling. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Adding appropriate amount of sulfuric acid and phosphoric acid into the leachate, adjusting pH, and adding 215.0g manganese dioxide. The stirring was turned on and the reaction vessel was heated, setting the reaction temperature at 90 ℃. After 4 hours of reaction, in order to promote the reaction to be complete, or remove redundant manganese dioxide, adding a proper amount of hydrogen peroxide, filtering, cleaning, drying, performing high-temperature treatment, crushing and screening to obtain purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, high-temperature treatment, crushing, sieving and the like to obtain the spherical trimanganese tetroxide.

Example 11

500.0g of ferromanganese phosphate (Mn) was weighed out separately_0.8Fe_0.2PO₄) Adding waste, 19.8g of iron powder and 60.0g of ethylene glycol into a reactor, adding about 1L of water, starting stirring and heating a reaction container, and setting the reaction temperature to be 120 ℃; preparing a 37.5 mass percent sulfuric acid solution, slowly adding the solution into the container, and adding 1500g in total. After 8 hours of reaction, the reaction mixture was cooled. Filtering to realize solid-liquid separation, and respectively obtaining leachate and filter residue. Adding appropriate amount of sulfuric acid and phosphoric acid into the leachate, adjusting pH, and adding 215.0g manganese dioxide. The stirring was turned on and the reaction vessel was heated, setting the reaction temperature at 90 ℃. After 6 hours of reaction, in order to promote the reaction to be complete, or remove redundant manganese dioxide, adding a proper amount of hydrogen peroxide, filtering, cleaning, drying, performing high-temperature treatment, crushing and screening to obtain purified ferric orthophosphate. Adding sodium hydroxide into the regeneration mother liquor, removing impurities while adjusting the pH value, and when the pH value is adjusted to be about 9, controlling the stirring speed and the feeding and discharging speed, and performing the working procedures of filtering, washing, drying, high-temperature treatment, crushing, sieving and the like to obtain the spherical trimanganese tetroxide.

In conclusion, the method takes the polyalcohol as the reducing agent and takes the high-valence manganese compound as the oxidizing agent, is used for recycling the regenerated phosphate waste, and is very efficient.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.

Claims (15)

1. A method for recycling and regenerating phosphate waste is characterized by comprising the following steps:

step 1, carrying out a dissolution reaction on powder containing phosphate wastes and a reducing agent in an acid solution to leach out metal elements and phosphate radicals contained in the phosphate wastes;

step 2, carrying out solid-liquid separation to remove insoluble substances;

step 3, adding an oxidant to carry out oxidation reaction on the leached metal element and phosphate radical to obtain a regenerated phosphate crude product;

step 4, cleaning, drying and screening the regenerated phosphate crude product to obtain a regenerated phosphate finished product;

wherein the reducing agent is selected from iron powder and at least one polyol; the oxidant is at least one of manganese dioxide, pyrolusite and manganous-manganic oxide.

2. The method of claim 1, wherein the phosphate waste contains phosphate having the general formula MPO₄Wherein the element M is at least one of metal elements Fe, Co, Ni, Mn and V.

3. The method according to claim 2, wherein the phosphate contained in the phosphate waste comprises any one or more of the following materials: FePO₄、MnPO₄、Fe_yMn_1-yPO₄（0<y<1）、CoPO₄、Fe_yCo_1-yPO₄（0<y<1）、NiPO₄、Fe_yNi_1-yPO₄（0<y<1) And VPO₄。

4. The method of claim 1, wherein the acidic solution is one or more of sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid.

5. The method of claim 3, wherein the phosphate is Fe_yMn_1-yPO₄（0<y<1) When used, the reducing agent comprises at least one polyol.

6. The method of claim 5, wherein the reducing agent is selected from one or more of ethylene glycol, glycerol, and 1, 2-propanediol.

7. The method for recycling and regenerating phosphate wastes according to claim 1, wherein a surfactant is added during the dissolution reaction of the phosphate waste-containing powder and the reducing agent in the acidic solution, and the molecular structure of the surfactant is as follows:

in the formula, substituent groups R1, R2, R3 and R4 are hydrogen or alkyl with 1-18 carbon atoms.

8. The method as claimed in claim 7, wherein the surfactant is selected from one or more of octyl trimethyl ammonium sulfate, decyl trimethyl ammonium sulfate, dodecyl trimethyl ammonium sulfate, and hexadecyl trimethyl ammonium sulfate.

9. The method according to claim 7, wherein the surfactant is 0.5 to 5% by mass of the phosphate waste.

10. The method for recycling and regenerating phosphate waste according to claim 1, wherein the reaction temperature is 0 to 150 ℃ and the reaction time is 0.1 to 72 hours when the phosphate waste and the reducing agent are dissolved in the acidic solution.

11. The method for recycling and regenerating phosphate waste according to claim 10, wherein the reaction temperature is 60 to 100 ℃ and the reaction time is 2 to 12 hours when the phosphate waste and the reducing agent are dissolved in the acidic solution.

12. The method for recycling and regenerating phosphate waste according to claim 1, wherein the reaction temperature is 0 to 100 ℃ and the reaction time is 0.1 to 24 hours during the oxidation reaction.

13. The method for recycling and regenerating phosphate waste according to claim 12, wherein the oxidation reaction is carried out at a temperature of 60 to 90 ℃ for 2 to 8 hours.

14. The method for recycling and regenerating phosphate waste according to any of claims 1 to 13,

step 21 is included between step 2 and step 3: adjusting the pH value, and removing impurities;

step 4 is followed by step 5: separating phosphate to obtain a regeneration mother liquor, removing impurities, adjusting the pH value of the regeneration mother liquor, and preparing a manganese regeneration product by a precipitation method, wherein the manganese regeneration product is manganese hydroxide or manganese oxide.

15. The method of claim 14, wherein in step 5, the manganese reprooducer is trimanganese tetroxide.

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