A rapid method for wet digestion of high-phosphorus iron ore

Abstract

The present invention provides a rapid method for wet digestion of high-phosphorus iron ore, which can quickly and accurately decompose high-phosphorus iron ore to meet the testing requirements of scientific research and industrial production for multi-element analysis of high-phosphorus iron ore. The present invention uses a mixed acid digestion method to decompose difficult-to-digest high-phosphorus iron ore, optimizes the addition ratio of each acid, determines the optimal decomposition conditions, and uses potassium dichromate titration and quinoline gravimetric method to respectively determine the iron and phosphorus content in the high-phosphorus iron ore. At the same time, the ICP standard curve method is used to analyze the content of impurity elements in the ore. Experimental results show that the sample is completely decomposed and the measurement results are reliable. This method is fast, convenient, and has good reproducibility, providing an accurate and rapid method for daily batch analysis of high-phosphorus iron ore.

Description

Technical Field

[0001] This invention belongs to the field of mineral analysis. This method provides a new approach and method for the rapid decomposition of high-phosphorus iron ore, which is of great significance for improving the resource utilization of phosphorus iron ore. This method can also be applied to the steel industry and iron ore processing, promoting the sustainable development of my country's iron ore industry. Background Art

[0002] my country has vast reserves of Ningxiang-style iron ore, making research on its resource utilization crucial. Ningxiang-style iron ore is primarily composed of oolitic hematite, with minor components of limonite, siderite, and chlorite. Iron grades typically range from 45% to 60%, and phosphorus grades from 0.45% to 1.15%. Hematite is a key raw material for ironmaking, and better utilization of this resource will have significant practical implications for the development of my country's steel industry.

[0003] High-phosphorus iron ore has a complex mineral composition and a high organic matter content. The complete digestion of the sample is the basis for accurately determining its elemental content. In order to decompose the high-phosphorus iron ore smoothly, the ore sample needs to be crushed to pass through a 150-mesh sieve. For a long time, the decomposition of high-phosphorus iron ore samples has always adopted the "alkali fusion acid leaching" mode, which has complicated steps, is time-consuming and energy-consuming, and there is an urgent need to explore more accurate and efficient detection methods. Invention patents CN110963746A and CN115367722A disclose the use of a single inorganic acid and phosphorus iron ore for sufficient acid leaching to achieve ore decomposition. The leached acid solution is prepared into high-quality battery-grade iron phosphate materials through a series of steps such as concentration, impurity removal, extraction, solid-liquid separation, crystallization, spray drying and calcination. However, in the decomposition process of phosphorus iron ore, single acid dissolution will cause problems such as long time consumption, no energy saving and slow analysis speed. Considering the above-mentioned energy consumption and efficiency problems, single acid dissolution cannot meet the needs of rapid detection and analysis of daily high-phosphorus iron ore batch samples. In addition, rapid and complete decomposition of the sample is a prerequisite for ensuring the accuracy of the composition analysis of high-phosphorus iron ore, which is directly related to the accurate evaluation of the utilization rate of valuable elements in the ore, especially the use of element content characteristics to provide strong support for the mining and utilization of high-phosphorus iron ore.

[0004] Based on the above research, it is necessary to provide a method for rapid digestion of high-phosphorus iron ore to ensure the accuracy of multi-element analysis, thereby accelerating the development and utilization of high-phosphorus iron ore in my country. Summary of the Invention

[0005] In view of the above, the object of the present invention is to provide a method for quickly and completely digesting high-phosphorus iron ore, using mixed acid wet digestion, optimizing the mixed acid ratio, and quantifying the heating process. Oxalic acid is a low-molecular organic acid with the ability to destroy silicate minerals and clay minerals in the sample, perfectly achieving complete decomposition of the ore. This method has a simple operating process, improves detection efficiency, can better meet the requirements of rapid analysis of high-phosphorus iron ore, and is suitable for application in large-scale industrial production. To this end, the present invention provides a rapid method for wet digestion of high-phosphorus iron ore, the method comprising the following steps:

[0006] S1: Weigh the sieved high-phosphorus iron ore sample and add ultrapure water to moisten it;

[0007] S2: Add a mixed acid system to S1 for digestion. After digestion, add oxalic acid, cover with a watch glass, and heat treat until the sample is completely dissolved. Remove and cool to room temperature.

[0008] S3: Completely transfer the above solution to a volumetric flask, dilute to the mark and shake well; filter the fixed volume solution through a microporous filter membrane to separate insoluble residues, and retain the filtrate as the main solution;

[0009] S4: Use a pipette to transfer the above main solution, and use potassium dichromate titration and quinolybdate gravimetric method to analyze the iron and phosphorus content in the mineral, and use ICP standard curve method to analyze the content of other elements in the ore.

[0010] In some embodiments, the mixing of raw materials or the digestion process of the present invention is carried out in a glass container, such as a triangular pancake, a digestion glass tube, etc.

[0011] The sample described in step S1 is a Ningxiang-type high-phosphorus iron ore from western Hubei. The iron in the ore is primarily present in the form of hematite, with small amounts of limonite, siderite, and trace magnetite. The phosphate mineral is primarily fluorapatite, with oolitic cores composed of oolitic chlorite, closely connected to the hematite and fluorapatite to form concentric layered structures. The iron grade is 45%-60%, and the phosphorus content is 0.45%-1.15%.

[0012] The sample mentioned in step S1 needs to be crushed until it passes through a 150-250 mesh sieve. The purpose of crushing and screening is to minimize impurities and maximize the specific surface area of ​​the ore after grinding. The water mentioned is ultrapure water, which should meet the specifications of GB / T 6682 Grade 2 water.

[0013] The mixed acid system described in step S2 is perchloric acid and sulfuric acid, the mass percentage concentration of sulfuric acid is 95.0%-98.0%, and the mass percentage concentration of perchloric acid is 70.0%-72.0%; the volume ratio of sulfuric acid to perchloric acid is 1-3:10-20.

[0014] The mass fraction of oxalic acid mentioned in step S2 is 99% or above, and the amount of oxalic acid added is 1-2 times the sample weight, so as to destroy silicate minerals and clay minerals in the sample and achieve complete digestion of the sample.

[0015] The heat treatment in step S2 adopts a two-stage heating method; first, low-temperature digestion is carried out, and the electric furnace temperature is set to 120°C-200°C. At this time, perchloric acid is used as the digestion main body, and the temperature is increased after the reaction is stable. After further reaction after oscillation, the temperature is increased to 290-400°C for digestion treatment, and digestion is completed after the liquid is clarified.

[0016] The specification of the volumetric flask in step S3 is 10mL-50mL.

[0017] The diameter of the microporous filtration membrane in step S3 is 0.2 μm-0.45 μm.

[0018] The specification of the pipette in step S4 is 1 mL-50 mL.

[0019] The specific operating steps of the potassium dichromate titration method and the quinolyl phosphate weight method described in step S2 can refer to the test method for iron and phosphorus content described in the standard HG / T4701-2021 "Iron Phosphate for Batteries".

[0020] The invention provides a rapid method for wet digestion of high-phosphorus iron ore, which has the following beneficial effects: the invention completely decomposes the high-phosphorus iron ore sample by adding a mixed acid system and an appropriate amount of oxalic acid and adopting a two-stage temperature rising treatment method, thereby avoiding the volatilization loss of the components to be measured, and the treated solution does not retain fine debris or powder of the original sample. The main content and trace components in the mineral are analyzed by potassium dichromate titration, quinolybdate gravimetric method and ICP standard curve method. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below to clearly and completely describe the digestion method provided by the present invention. However, the scope of protection of the present invention is not limited to the following specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The contents of the following embodiments are configured according to the proportional relationship of the summary of the invention.

[0022] Example 1

[0023] A rapid method for wet digestion of high-phosphorus iron ore, specifically comprising the following steps:

[0024] Step S1: Weigh 0.2 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water.

[0025] Step S2: Add 2 mL of perchloric acid (70% by mass) and 15 mL of sulfuric acid (98% by mass) to the beaker (i.e., a volume ratio of perchloric acid to sulfuric acid of 2:15). Cover with a watch glass. Place the beaker on a 200°C electric furnace for low-temperature digestion. When brown smoke appears and a large amount of foam forms on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 400°C until thick white smoke appears. Continue digestion until a small amount of white smoke remains at the bottom of the beaker. Add 0.3 g of oxalic acid (i.e., 1.5 times the amount of oxalic acid used relative to the ore) and continue digestion until the solution in the beaker becomes clear. Remove the beaker and let it cool to room temperature.

[0026] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0027] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0028] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0029] Example 2

[0030] The method and conditions were the same as in Example 1, except for the temperature of the digestion.

[0031] A rapid method for wet digestion of high-phosphorus iron ore, specifically comprising the following steps:

[0032] Step S1: Weigh 0.2 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water.

[0033] Step S2: Add 2 mL of perchloric acid (70% by mass) and 15 mL of sulfuric acid (98% by mass) to the beaker (i.e., a volume ratio of perchloric acid to sulfuric acid of 2:15). Cover with a watch glass. Place the beaker on an electric stove at 180°C for low-temperature digestion. When brown smoke emerges from the beaker and a large amount of foam forms on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 350°C until thick white smoke emerges. Continue digestion until a small amount of white smoke remains at the bottom of the beaker. Add 0.3 g of oxalic acid (i.e., 1.5 times the amount of oxalic acid used relative to the ore) and continue digestion until the solution in the beaker becomes clear. Remove the beaker and let it cool to room temperature.

[0034] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0035] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0036] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0037] Example 3

[0038] The method and conditions were the same as in Example 1, except that the amount of oxalic acid was changed to 0.4 g.

[0039] A rapid method for wet digestion of high-phosphorus iron ore, specifically comprising the following steps:

[0040] Step S1: Weigh 0.2 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water.

[0041] Step S2: Add 2 mL of perchloric acid (70% by mass) and 15 mL of sulfuric acid (98% by mass) to the beaker (i.e., a volume ratio of perchloric acid to sulfuric acid of 2:15). Cover with a watch glass. Place the beaker on a 200°C electric furnace for low-temperature digestion. When brown smoke appears and a large amount of foam forms on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 400°C until thick white smoke appears. Continue digestion until a small amount of white smoke remains at the bottom of the beaker. Add 0.4 g of oxalic acid (i.e., the amount of oxalic acid used is twice that of the ore) and continue digestion until the solution in the beaker becomes clear. Remove the beaker and let it cool to room temperature.

[0042] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0043] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0044] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0045] Example 4

[0046] The method and conditions were the same as in Example 1, except that the amount of perchloric acid added was changed to 3 mL.

[0047] A rapid method for wet digestion of high-phosphorus iron ore, specifically comprising the following steps:

[0048] Step S1: Weigh 0.2 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water.

[0049] Step S2: Add 3 mL of perchloric acid (70% by mass) and 15 mL of sulfuric acid (98% by mass) to the beaker (i.e., a volume ratio of perchloric acid to sulfuric acid of 2:15). Cover with a watch glass. Place the beaker on a 200°C electric furnace for low-temperature digestion. When brown smoke appears and a large amount of foam forms on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 400°C until thick white smoke appears. Continue digestion until a small amount of white smoke remains at the bottom of the beaker. Add 0.3 g of oxalic acid (i.e., 1.5 times the amount of oxalic acid used relative to the ore) and continue digestion until the solution in the beaker becomes clear. Remove the beaker and let it cool to room temperature.

[0050] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0051] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0052] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0053] Example 5

[0054] The method and conditions were the same as those in Example 1, except that the amount of sulfuric acid was 20 mL and the sample weight was 0.4 g.

[0055] A rapid method for wet digestion of high-phosphorus iron ore, specifically comprising the following steps:

[0056] Step S1: Weigh 0.4 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water.

[0057] Step S2: Add 2 mL of perchloric acid (70% by mass) and 20 mL of sulfuric acid (98% by mass) to the beaker (i.e., a volume ratio of perchloric acid to sulfuric acid of 2:15). Cover with a watch glass. Place the beaker on a 200°C electric furnace for low-temperature digestion. When brown smoke appears and a large amount of foam forms on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 400°C until thick white smoke appears. Continue digestion until a small amount of white smoke remains at the bottom of the beaker. Add 0.3 g of oxalic acid (i.e., 1.5 times the amount of oxalic acid used relative to the ore) and continue digestion until the solution in the beaker becomes clear. Remove the beaker and let it cool to room temperature.

[0058] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0059] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0060] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0061] Comparative Example 1

[0062] The method and conditions were the same as in Example 1, except that sulfuric acid was used as the digestion solution, resulting in incomplete digestion of the sample.

[0063] Step S1: Weigh 0.2 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water;

[0064] Step S2: Add 15 mL of sulfuric acid (98% by mass) to the beaker and cover with a watch glass. Place the beaker on a 200°C electric furnace for low-temperature digestion. When brown smoke appears and a large amount of foam appears on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 400°C until thick white smoke appears. Continue digestion until a small amount of white smoke remains at the bottom of the beaker. Add 0.3 g of oxalic acid (i.e., 1.5 times the amount of oxalic acid used for the ore) and continue digestion. If the sample is not completely digested, remove the beaker and let it cool to room temperature.

[0065] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0066] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0067] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0068] Comparative Example 2

[0069] The method and conditions were the same as in Example 1, except that the digestion solution was perchloric acid, and the sample digestion was incomplete.

[0070] Step S1: Weigh 0.2 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water;

[0071] Step S2: Add 2 mL of perchloric acid (70% by mass) to the beaker and cover with a watch glass. Place the beaker on a 200°C electric stove for low-temperature digestion. When brown smoke appears and a large amount of foam appears on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 400°C until thick white smoke appears. Continue digestion until a small amount of white smoke remains at the bottom of the beaker. Add 0.3 g of oxalic acid (i.e., 1.5 times the amount of oxalic acid used for the ore) and continue digestion. If the sample is not completely digested, remove the beaker and let it cool to room temperature.

[0072] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0073] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0074] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0075] Comparative Example 3

[0076] The method and conditions were the same as in Example 1, except that oxalic acid was not added. The sample digested slowly and was accompanied by a small amount of insoluble impurities.

[0077] A rapid method for wet digestion of high-phosphorus iron ore, specifically comprising the following steps:

[0078] Step S1: Weigh 0.2 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water;

[0079] Step S2: Add 2 mL of perchloric acid (70% by mass) to the beaker and cover with a watch glass. Place the beaker on a 200°C electric furnace for low-temperature digestion. When brown smoke appears in the bottle and a large amount of foam appears on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 400°C until thick white smoke appears. Continue digestion until a small amount of white smoke remains at the bottom of the bottle. Continue digestion. The sample digestion is slow and accompanied by a small amount of insoluble impurities. Remove the beaker and let it cool to room temperature.

[0080] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0081] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0082] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0083] Comparative Example 4

[0084] The method and conditions were the same as in Example 1, except that the volume ratio of perchloric acid to sulfuric acid was changed to 1:25.

[0085] A rapid method for wet digestion of high-phosphorus iron ore, specifically comprising the following steps:

[0086] Step S1: Weigh 0.2 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water.

[0087] Step S2: Add 1 mL of perchloric acid (70% by mass) and 25 mL of sulfuric acid (98% by mass) to the beaker (i.e., a volume ratio of perchloric acid to sulfuric acid of 1:25). Cover with a watch glass. Place the beaker on a 200°C electric furnace for low-temperature digestion. When brown smoke appears and a large amount of foam forms on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 400°C until thick white smoke appears. Continue digestion until a small amount of white smoke remains at the bottom of the beaker. Add 0.3 g of oxalic acid (i.e., 1.5 times the amount of oxalic acid used relative to the ore) and continue digestion until the solution in the beaker becomes clear. Remove the beaker and let it cool to room temperature.

[0088] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0089] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0090] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0091] Comparative Example 5

[0092] The method and conditions were the same as in Example 1, except that the volume ratio of perchloric acid to sulfuric acid was changed to 4:10.

[0093] A rapid method for wet digestion of high-phosphorus iron ore, specifically comprising the following steps:

[0094] Step S1: Weigh 0.2 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water.

[0095] Step S2: Add 4 mL of perchloric acid (70% by mass) and 10 mL of sulfuric acid (98% by mass) to the beaker (i.e., a volume ratio of perchloric acid to sulfuric acid of 4:10). Cover with a watch glass. Place the beaker on a 200°C electric furnace for low-temperature digestion. When brown smoke appears and a large amount of foam appears on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 400°C until thick white smoke appears. Continue digestion until a small amount of white smoke remains at the bottom of the beaker. Add 0.3 g of oxalic acid (i.e., 1.5 times the amount of oxalic acid used relative to the ore) and continue digestion until the solution in the beaker becomes clear. Remove the beaker and let it cool to room temperature.

[0096] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0097] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0098] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0099] Comparative Example 6

[0100] The method and conditions were the same as in Example 1, except that oxalic acid was replaced by acetic acid.

[0101] A rapid method for wet digestion of high-phosphorus iron ore, specifically comprising the following steps:

[0102] Step S1: Weigh 0.2 g of high-phosphorus iron ore that has passed through a 150-mesh sieve into a conical beaker and moisten it with 10 mL of ultrapure water.

[0103] Step S2: Add 2 mL of perchloric acid (70% by mass) and 15 mL of sulfuric acid (98% by mass) to the beaker (i.e., a volume ratio of perchloric acid to sulfuric acid of 2:15). Cover with a watch glass. Place the beaker on a 200°C electric stove for low-temperature digestion. When brown smoke appears and a large amount of foam forms on the liquid surface, begin shaking the beaker. When uniform and large foam appears on the liquid surface, stop shaking the beaker and heat it to 400°C until thick white smoke appears. Continue digestion until a small amount of white smoke remains at the bottom of the beaker. Add 0.3 g of acetic acid (i.e., 1.5 times the amount of acetic acid used for the ore) and continue digestion until the solution in the beaker becomes clear. Remove the beaker and let it cool to room temperature.

[0104] S3: The cooled solution was completely transferred to a 100 mL volumetric flask, diluted to the mark and shaken to mix; the fixed volume solution was filtered through a microporous filter membrane with a pore size of 0.25 μm, and the filtrate was retained as the main solution.

[0105] S4: Use a 25 mL pipette to transfer the above main solution, and use potassium dichromate titration and quinoline molybdate gravimetric method to analyze the iron and phosphorus content in the mineral.

[0106] S5: Use a 1 mL pipette to transfer the above main solution, dilute it to 250 mL with ultrapure water, and then use the ICP standard curve method to analyze the content of other elements in the ore.

[0107] Table 1 Elemental analysis results of wet digestion examples 1-5 and comparative examples 1-6 high phosphorus iron ore samples

[0108] As shown in Table 1, from the results of Examples 1-5, the results of the determination of iron and phosphorus by titration and gravimetric method are similar to the results of the ICP standard curve method analysis, and the two methods have good reproducibility and accurate results. From the results of the comparative example, the determination results are on the low side due to incomplete digestion. In summary, the method of the present invention can provide an accurate and rapid method for daily high-phosphorus iron ore batch analysis.

[0109] As described above, the above embodiments are only for illustrating the technical concept and features of the present invention, and those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and purpose of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A rapid method for wet digestion of high-phosphorus iron ore, characterized in that The wet digestion comprises the following steps: S1: Weigh the sieved high-phosphorus iron ore sample and add ultrapure water to moisten it; S2: Add a mixed acid system to S1 for digestion, wherein the mixed acid system comprises perchloric acid and sulfuric acid, wherein the mass percentage concentration of sulfuric acid is 95.0%-98.0%, and the mass percentage concentration of perchloric acid is 70.0%-72.0%; the volume ratio of sulfuric acid to perchloric acid is 1-3:10-20, cover with a watch glass, and perform heat treatment. After the heat treatment, add oxalic acid in an amount of 1-2 times the sample weight, until the sample is completely dissolved, remove and cool to room temperature; The heat treatment adopts a two-stage heating method; first, low-temperature digestion, the electric furnace temperature is set to 120°C-200°C, and when the perchloric acid decomposition temperature is reached, after further oscillation and further reaction, the temperature is raised to 290°C-400°C for digestion treatment, and digestion is continued until the liquid is clear. S3: Completely transfer the above solution to a volumetric flask, dilute to the mark and shake well; filter the fixed volume solution through a microporous filter membrane to separate insoluble residues, and retain the filtrate as the main solution; S4: Use a pipette to transfer the above main solution, and use potassium dichromate titration and quinolybdate gravimetric method to analyze the iron and phosphorus content in the mineral, and use ICP standard curve method to analyze the content of other elements in the ore.

2. A rapid method for wet digestion of high-phosphorus iron ore according to claim 1, characterized in that, The sample described in step S1 is a Ningxiang-type high-phosphorus iron ore in western Hubei, with an iron grade of 45%-60% and a phosphorus content of 0.45%-1.15%.

3. A rapid method for wet digestion of high-phosphorus iron ore according to claim 1, characterized in that, The sample mentioned in step S1 needs to be crushed to pass through a 150-250 mesh sieve.

4. A rapid method for wet digestion of high-phosphorus iron ore according to claim 1, characterized in that, The mass fraction of oxalic acid mentioned in step S2 is greater than 99%.

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