Red mud iron recovery method matched with expired drugs and pharmaceutical wastewater

Abstract

The application discloses a kind of cooperation expired medicine, bauxite iron recovery method of pharmaceutical wastewater, comprising the following steps: S1, bauxite is crushed, grinds, and then mixed with hydrogen peroxide solution, and bauxite slurry is prepared;S2, the expired medicine, pharmaceutical wastewater after crushing is added in bauxite slurry, and is prepared as reaction raw material;S3, after stirring, reaction raw material is added in high temperature and high pressure reaction kettle, and after reaching supercritical state, electric heating is closed, and reaction is carried out by relying on oxidation self-heating until end;S4, after cooling, gas-liquid separation is carried out, and liquid-solid mixture is carried out magnetic separation, and Fe3O4 is recovered.The application realizes the dealkalization treatment of bauxite, and the iron in bauxite is stably recovered, and the remaining solid components can be better utilized, and due to the supercritical water oxidation on organic matter super strong oxidizability, the expired medicine in system is completed harmless degradation, and the heat generated by organic matter oxidation is relied on to reduce energy consumption cost.

Description

Technical Field

[0001] This invention belongs to the field of waste disposal and resource recycling technology, specifically relating to a method for recovering red mud iron in conjunction with expired medicines and pharmaceutical wastewater. Background Technology

[0002] There are many types of pharmaceuticals, such as penicillin, cephalosporins, tetracyclines, erythromycin, quinolones, and nitroimidazoles, all of which are antibiotics primarily composed of organic matter. Expired pharmaceuticals experience a decrease in the content of their active ingredients but may produce toxic and harmful substances. The disposal of expired pharmaceuticals has always been handled by medical waste management companies for collection and centralized treatment. Pharmaceutical wastewater generated during drug production is a type of high-concentration organic wastewater that is difficult to treat. It contains not only large amounts of heavy metals and harmful chemicals but also non-degradable pollutants, along with various acids, alkalis, tannins, and anthraquinones. If not treated properly, it will have many negative environmental impacts and hinder the sustainable development of the pharmaceutical industry.

[0003] Red mud, a solid waste generated in the alumina industry, is characterized by high reserves, high yield, and high alkalinity. It contains a large amount of iron, with the Fe2O3 content ranging from 20% to 60% depending on the bauxite's texture and the alumina production process. Although studies have used calcination-sulfuric acid leaching to extract iron from red mud, the recovery rate fluctuates between 0.3% and 97%. The high alkalinity of red mud has been a significant obstacle to its utilization. Water washing methods require large amounts of water, are time-consuming, and have limited dealkali removal effects; acid leaching uses large amounts of acid and easily generates secondary pollution; lime methods consume large amounts of lime, sometimes require heating, and are costly; biological methods have too long a cycle and are mainly used for the remediation of red mud dumps. If expired pharmaceutical products and wastewater could be used for red mud disposal and resource recovery, it would undoubtedly be more environmentally friendly. Currently, no technical solutions have been reported for the joint disposal of expired pharmaceutical products, wastewater, and red mud. Therefore, it is essential to develop a red mud iron recovery method that can be used in conjunction with expired pharmaceutical products and wastewater. Summary of the Invention

[0004] The purpose of this invention is to provide a method for recovering iron from red mud in conjunction with expired medicines and pharmaceutical wastewater.

[0005] The objective of this invention is achieved by including the following steps: S1. Crush and grind the red mud, then mix it with hydrogen peroxide solution to make red mud slurry; S2. Add the crushed expired medicines and pharmaceutical wastewater to the red mud slurry to prepare the reaction raw materials; S3. After stirring the reactants, add them to an electrically heated high-temperature and high-pressure reactor. Once the reactor reaches a supercritical state (temperature reaches 375℃, pressure reaches 22.1MPa), turn off the electric heating and allow the reaction to proceed by autothermal oxidation until completion. The following reactions occur in the high-temperature and high-pressure reactor: 3Fe₂O₃ + 2CO = 2Fe₃O₄ + 2CO₂ CO2 + 2OH- = CO3 2- +H2O S4. After cooling, gas and liquid are separated. The main gas phase products are CO, CH4, CO2, and N2. The liquid is high-COD pharmaceutical wastewater. The solid is reduced magnetic iron oxide and red mud residue. The liquid-solid mixture is subjected to magnetic separation to recover Fe3O4.

[0006] Preferably, in step S1, the grinding particle size is no higher than 150 mesh, the hydrogen peroxide concentration is 30% (30% is a mass fraction), and 1g of dry red mud is prepared for every 6ml of hydrogen peroxide solution.

[0007] Preferably, the COD of the pharmaceutical wastewater in step S2 is greater than 6000 mg / L, and the volume ratio of pharmaceutical wastewater to hydrogen peroxide solution is 2:3.

[0008] Preferably, in step S2, the quality of the expired drug is the same as the dry weight of the red mud, and the particle size of the expired drug is no higher than 3 mm.

[0009] Preferably, in step S3, the reaction raw materials are stirred at room temperature for 15 minutes, and the sedimentation ratio of red mud in the solution does not exceed 5% (5% is a mass fraction).

[0010] Preferably, the heating process in step S3 does not exceed 4 hours.

[0011] Preferably, the liquid obtained from the liquid-solid mixture separation in step S4 is sent to step S2 for use in pharmaceutical wastewater treatment.

[0012] The beneficial effects of this invention are: 1. This invention utilizes supercritical water oxidation to decompose and oxidize expired pharmaceuticals and pharmaceutical wastewater. The CO generated from incomplete oxidation reduces Fe2O3 in red mud to Fe3O4. The acidic CO2 neutralizes the alkaline components released from the red mud in the system, promoting a rightward shift in the Fe2O3 reduction reaction. This invention achieves dealkalization of red mud and stably recovers iron from it. The remaining solid components can be better utilized. Furthermore, due to the strong oxidizing power of supercritical water oxidation on organic matter, expired pharmaceuticals in the system undergo harmless degradation. Energy costs are reduced by relying on the heat generated from the oxidation of organic matter. 2. Red mud contains a large amount of metal oxides, mainly Fe2O3, Al2O3, and TiO2. These metal oxides can act as catalysts in the supercritical water oxidation process, accelerating the oxidation rate of expired drugs, reducing reaction time, and lowering the risk of equipment corrosion. However, controlling the raw material ratio during oxidation is crucial. A significant amount of CO is generated during oxidation. Sufficient CO in the supercritical water system reduces Fe2O3 in the red mud to Fe3O4, producing new CO2 which is gradually absorbed and fixed in a highly alkaline environment during the high-temperature stage and the cooling to room temperature stage, ultimately resulting in a weakly acidic liquid. The resulting solids, after magnetic separation, yield Fe3O4 with a purity of 30%–60% (mass fraction). The remaining solids after magnetic separation are mainly silica and sodium aluminum silicate hydrate, the latter being widely used in industries such as coatings, inks, plastics, rubber, leather, printing and dyeing, and papermaking. The remaining high-COD pharmaceutical wastewater can be used as raw material in secondary reactions. This invention is applicable to the vast majority of expired drugs, including not only common antibiotics but also traditional Chinese medicines. This method is best suited for cyclic supercritical systems, maximizing the oxidation of expired pharmaceuticals and the recovery of iron from red mud through cyclic reactions; 3. This invention uses electric heating to reach the supercritical water state. After reaching the supercritical water state, it relies on the heat generated by the oxidation of organic matter to maintain the supercritical state. This saves energy and allows the reaction process inside the reactor to be judged by the temperature change. It degrades expired drugs and also completes the dealkalization treatment of red mud and the recovery of iron resources. Attached Figure Description

[0013] Figure 1 This is a process flow diagram of the present invention; Figure 2 The images show the XRD patterns of the original red mud and the solids after magnetic separation. Detailed Implementation

[0014] The present invention will be further described below with reference to the embodiments and accompanying drawings, but this does not limit the present invention in any way. Any changes or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0015] Example 1 As attached Figure 1 As shown, this embodiment describes a method for recovering iron from red mud in conjunction with expired medicines and pharmaceutical wastewater, including the following steps: S1. Crush and grind the red mud to a particle size of no more than 150 mesh, then mix it with a 30% hydrogen peroxide solution. For every 6 ml of hydrogen peroxide solution, mix 1 g of dry red mud to make a red mud slurry. S2. Add the crushed expired drugs and pharmaceutical wastewater to the red mud slurry to prepare the reaction raw materials; the COD of the pharmaceutical wastewater is greater than 6000 mg / L, the volume ratio of pharmaceutical wastewater to hydrogen peroxide solution is 2:3, the mass of the expired drugs is the same as the dry weight of the red mud, and the particle size of the expired drugs is not higher than 3 mm. S3. Stir the reaction raw materials at room temperature for 15 minutes, then add them to a high-temperature and high-pressure reactor. The heating process shall not exceed 4 hours. After reaching the supercritical state, turn off the electric heating and let the reaction continue by oxidation and self-heating until the end. S4. After cooling, gas and liquid are separated, and the liquid-solid mixture is magnetically separated to recover Fe3O4.

[0016] Example 2 This embodiment, in conjunction with the red mud iron recovery method for expired drugs and pharmaceutical wastewater, is based on Embodiment 1, wherein the liquid obtained from the liquid-solid mixture separation in step S4 is sent to step S2 for use in pharmaceutical wastewater.

[0017] Example 3 The sample red mud was pulverized in a small high-speed pulverizer for 30 minutes, then sieved through a 150-mesh sieve. The sieved red mud powder was dried in an oven at 60°C for 6 hours. 20g of the dried red mud was weighed and added to 120mL of a 30% hydrogen peroxide solution to prepare a red mud slurry. 20g of expired oseltamivir granules were weighed and added to the prepared red mud slurry. 80mL of fermented pharmaceutical wastewater (containing antibiotics, vitamins, amino acids, nucleic acids, organic acids, coenzymes, enzyme inhibitors, hormones, immunomodulatory substances, etc.) was added to prepare the reaction raw material, with a COD of 8500mg / L. After stirring for 15 minutes, the mixture was poured into a reaction vessel with an effective volume of 500 mL. After 2 hours and 10 minutes, the temperature reached 384.3℃ and 23 MPa. The heating power was then turned off, and the mixture was allowed to react spontaneously before cooling to room temperature. After cooling, the gas pressure was 1.23 MPa. The pressure was reduced to 0.2 MPa using a pressure reducing valve, and the gas was collected. The liquid-solid mixture was then collected by opening the vessel lid. The mixture was subjected to solid-liquid separation. A sample of the separated liquid was taken for COD determination, which was 7620 mg / L. The solid was ground, and the magnetic separation rate was 43.6%. The remaining solid was analyzed by flame atomic absorption spectrometry, and the dealkali removal rate of the red mud was found to be 61.1%.

[0018] Example 4 The sample red mud was pulverized in a small high-speed pulverizer for 30 minutes, then sieved through a 150-mesh sieve. The sieved red mud powder was dried in an oven at 60°C for 6 hours. 20g of the dried red mud was weighed and added to 120mL of a 30% hydrogen peroxide solution to prepare a red mud slurry. 20g of expired tetracycline tablets was pulverized in the small high-speed pulverizer and added to the prepared red mud slurry. 80mL of chemically synthesized pharmaceutical wastewater with a COD of 7620mg / L (this type of wastewater has a higher content of heavy metal ions than fermentation wastewater, and its organic components include phenols, ketones, aldehydes, esters, ethers, nitriles, cycloalkanes, etc.) was added. The reaction raw materials were stirred for 15 minutes and then poured into a reaction vessel with an effective volume of 500 mL. After 2 hours and 12 minutes, the temperature reached 385.1℃ and 23 MPa. The heating power was turned off, and the mixture was allowed to react spontaneously before cooling to room temperature. After cooling, the gas pressure was 1.25 MPa. The pressure was reduced to 0.2 MPa using a pressure reducing valve, and the gas was collected. The liquid-solid mixture was collected by opening the vessel lid. The liquid-solid mixture after reaction was subjected to solid-liquid separation. The COD of the separated liquid was measured to be 7980 mg / L. The solid was ground, and the magnetic separation rate was 39.8%. The remaining solid was analyzed by flame atomic absorption spectrometry, and the dealkali removal rate of the red mud was found to be 63.5%. Figure 2 The image shows the XRD pattern of the experimental results in Example 4. After the red mud, chemically synthesized pharmaceutical wastewater, and tetracycline tablets reacted in a supercritical system, the sodalite phase disappeared and decomposed into simple minerals. These minerals reacted with the generated CO2 to produce sodium aluminum silicate carbonate. The original Fe2O3 reacted with the generated CO in the reaction and was reduced to magnetic Fe3O4.

Claims

1. A method for recovering iron from red mud mixed with expired medicines and pharmaceutical wastewater, characterized by, Includes the following steps: S1. Crush and grind the red mud, then mix it with hydrogen peroxide solution to make red mud slurry; The grinding particle size is no higher than 150 mesh, the hydrogen peroxide concentration is 30%, and 1g of dry red mud is added for every 6ml of hydrogen peroxide solution. S2. Add the crushed expired drugs and pharmaceutical wastewater to the red mud slurry to prepare the reaction raw materials; the COD of the pharmaceutical wastewater is greater than 6000 mg / L, and the volume ratio of pharmaceutical wastewater to hydrogen peroxide solution is 2:3; the mass of the expired drugs is the same as the dry weight of the red mud, and the particle size of the expired drugs is not higher than 3 mm. S3. After stirring the reaction raw materials, add them to the high-temperature and high-pressure reactor. After reaching the supercritical state, turn off the electric heating and rely on the self-heating of oxidation to carry out the reaction until it is completed. Stir the reaction raw materials at room temperature for 15 minutes. The proportion of red mud settling in the solution should not exceed 5%. Control the ratio of raw materials during the oxidation process. A large amount of CO is generated during the oxidation process. Sufficient CO in the supercritical water system reduces Fe2O3 in red mud to Fe3O4. The acidic CO2 neutralizes the alkaline components released from red mud in the system, promoting the reduction reaction of Fe2O3 to shift to the right. S4. After cooling, gas and liquid are separated, and the liquid-solid mixture is magnetically separated to recover Fe3O4. The liquid obtained from the separation of the liquid-solid mixture is sent to step S2 for use in pharmaceutical wastewater treatment.

2. The method of claim 1, wherein the method is characterized by The heating process in step S3 should not exceed 4 hours.

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