Method for detecting content of potassium element in molybdenum concentrate

Abstract

The invention relates to the technical field of analytical chemistry and mineral detection, in particular to a method for detecting potassium element in molybdenum concentrate, which comprises preparation, working curve solution preparation and inductively coupled plasma emission spectrometer detection. Through acid digestion, microwave treatment and instrument parameter optimization, the problem of matrix interference is solved, the detection sensitivity and efficiency are improved, the detection limit is greatly reduced, and the standard recovery rate is improved. The method is suitable for rapid quality monitoring of molybdenum concentrate, can be expanded to detection of other potassium-containing minerals, is combined with automatic equipment or an online monitoring system, improves the detection consistency and real-time performance, and has important application value.

Description

Technical Field

[0001] This invention relates to the field of material element content detection technology, and in particular to a method for detecting potassium content in molybdenum concentrate. Background Technology

[0002] The main component of molybdenum concentrate is MoS2, which is lead-gray, similar to graphite, and has a metallic luster. It belongs to the hexagonal crystal system, is soft and slippery, and is thin and flexible. Its specific gravity is 4.7–4.8, hardness is 1–1.5, and melting point is 795℃. Molybdenite, rich in molybdenum concentrate, often contains associated minerals such as orthoclase, mica, barite-iron mica, and illite. Potassium in these associated minerals can accumulate during production, becoming an impurity in the molybdenum concentrate. The presence of potassium not only increases the potassium content in molybdenum products, affecting their purity and quality, but also exacerbates material caking during smelting, affecting the normal operation of production equipment. Therefore, in-depth research on methods for detecting potassium in molybdenum concentrate has significant theoretical and practical implications.

[0003] Current industry standards specify flame atomic absorption spectrometry (FAS) for the determination of potassium in molybdenum concentrate. However, in actual production, existing detection techniques are complex and inefficient, hindering production guidance. Therefore, there is an urgent need to establish a rapid, accurate, and reliable method for determining potassium in molybdenum concentrate, providing data support for process control and product quality assurance.

[0004] Patent CN118883214A discloses a method for detecting magnesium content in molybdenum concentrate, relating to the field of elemental content detection technology. The specific steps include weighing 0.1-0.2 g of molybdenum concentrate sample, accurate to 0.0001 g; preparing a molybdenum concentrate sample solution and a molybdenum concentrate blank solution; preparing a working curve solution; and performing the detection. This method eliminates the need for complex operations such as separation and enrichment during sample pretreatment, requiring only acid treatment to complete the detection. It can instantly display the magnesium content in the sample, significantly shortening the measurement time. However, this method mainly targets the detection of magnesium and does not address the determination of potassium, and its resistance to interference in complex matrices requires further verification.

[0005] Patent CN114878487A discloses a method for detecting gold content in molybdenum concentrate, belonging to the field of mineral analysis and testing technology. This method involves steps such as low-temperature roasting in a muffle furnace, dissolving the sample, adding lead acetate and perchloric acid, and finally using an atomic absorption spectrophotometer to determine the absorbance of gold and calculate the gold content. This method is simple to operate and provides accurate and reliable results; however, its target element is gold, and it does not involve the detection of potassium. Furthermore, there is still room for improvement in selectivity and sensitivity under conditions of multiple elements coexisting.

[0006] In summary, while existing technologies have made some progress in the detection of specific elements in molybdenum concentrate, there is still a lack of targeted technical solutions for the detection of potassium, especially as the need for rapid and accurate detection in complex matrices has not been fully met. Summary of the Invention

[0007] This invention provides a method for detecting potassium in molybdenum concentrate, aiming to achieve rapid, accurate, and reliable determination of potassium in molybdenum concentrate by optimizing sample pretreatment and detection procedures. This method eliminates the need for complex separation, enrichment, or impurity shielding operations during analysis; sample preparation can be completed with only simple acid dissolution and dilution steps. Simultaneously, high-sensitivity detection is achieved using inductively coupled plasma atomic emission spectrometry (ICP-AES), providing data support for process control and product quality assurance in molybdenum concentrate production.

[0008] In a first aspect, the present invention provides a method for detecting the potassium content in molybdenum concentrate, the method comprising the steps of:

[0009] S1. Preparation of molybdenum concentrate sample solution and blank solution:

[0010] Two polytetrafluoroethylene digestion tubes were used as a molybdenum concentrate sample tube and a blank sample tube, respectively. 0.1000~0.1500g of molybdenum concentrate sample, 1mL of hydrochloric acid, 2mL of nitric acid and 1mL of hydrofluoric acid were added to the molybdenum concentrate sample tube in sequence. 1mL of hydrochloric acid, 2mL of nitric acid and 1mL of hydrofluoric acid were added to the blank sample tube.

[0011] The molybdenum concentrate sample tube and the blank sample tube were subjected to microwave digestion. The carrier liquid used for microwave digestion included 150 mL of deionized water and 5 mL of nitric acid.

[0012] After digestion, place the sample on an acid-removing apparatus at 200℃ until the white fumes disappear. After cooling, add 5 mL of hydrochloric acid solution (1+1) and heat to dissolve on the acid-removing apparatus. After cooling again, dilute to 100 mL with deionized water to obtain the molybdenum concentrate sample solution and blank solution.

[0013] S2. Preparation of working curve solution:

[0014] Take 10.00 mL of potassium single-element standard stock solution with a mass concentration of 1000 μg / mL into a 100 mL volumetric flask, dilute with water to the mark, mix well, and obtain 1 mL of potassium standard solution containing 100 μg potassium.

[0015] Transfer 1 mL, 5 mL and 10 mL of the potassium standard solution into three 100 mL volumetric flasks within a 10 mL range. Take an empty 100 mL volumetric flask and add 10 mL of hydrochloric acid solution (1+1) to each of the four volumetric flasks. Dilute with water to the mark, mix well, and obtain a set of working curve solutions.

[0016] S3, Detection:

[0017] A set of working curve solutions of S2 were placed on an inductively coupled plasma atomic emission spectrometer to measure the spectral intensity of potassium, thus obtaining a standard working curve starting from the blank value.

[0018] The molybdenum concentrate sample solution and blank solution from S1 are placed on an ion emission spectrometer. After subtracting the blank value, the percentage content of potassium in the sample solution is determined from the standard working curve.

[0019] Furthermore, the acid reagents used in microwave digestion are hydrochloric acid, nitric acid, and hydrofluoric acid, with a volume ratio of 1:2:1.

[0020] Furthermore, the pre-pressurization of microwave digestion is set to 3 MPa-5 MPa, the maximum temperature is set to 180℃-220℃, and the holding time is set to 10 min-20 min.

[0021] Furthermore, the pre-pressurization of microwave digestion was set to 4 MPa, the maximum temperature was set to 200°C, and the holding time was set to 15 min.

[0022] Furthermore, in step S1, the digestion tube wall is rinsed before heating and dissolving on the acid-removing apparatus.

[0023] Furthermore, the radio frequency power of the inductively coupled plasma atomic emission spectrometer was set to 1200W, the auxiliary gas flow rate to 1.0L / min, the sample flow rate to 1.0~5.0mL / min, the potassium spectral line to be selected to be 766.491nm, and the argon purity to be ≥99.99%.

[0024] Furthermore, the procedure also includes the following steps: selecting two molybdenum concentrate samples from different sources, labeling them as molybdenum concentrate sample No. 1 and molybdenum concentrate sample No. 2 respectively, performing repeated measurements multiple times according to steps S1-S3, recording the results of each measurement, and calculating the average value and relative standard deviation.

[0025] Furthermore, the method includes the following steps: after the sample solution prepared in step S1 is cooled, a certain amount of potassium standard solution is added, and the sample is re-measured according to steps S2 and S3 to calculate the spiked recovery rate.

[0026] In summary, the present invention provides a method for detecting potassium in molybdenum concentrate. By subjecting the molybdenum concentrate sample to acid digestion and microwave treatment, the potassium in the sample is completely released and enters the solution system, avoiding the complex matrix separation process in traditional methods. Simultaneously, by introducing hydrochloric acid solution (1+1) for subsequent treatment of the sample solution, matrix interference is further suppressed, improving the accuracy of the detection results. Furthermore, the use of inductively coupled plasma atomic emission spectrometry (ICP-AES) for high-sensitivity potassium detection meets the needs of efficient and rapid detection of potassium content in molybdenum concentrate in actual production. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] In a first aspect, the present invention provides a method for detecting the potassium content in molybdenum concentrate, the method comprising the steps of:

[0029] S1. Preparation of molybdenum concentrate sample solution and blank solution:

[0030] Two polytetrafluoroethylene digestion tubes were used as a molybdenum concentrate sample tube and a blank sample tube, respectively. 0.1000~0.1500g of molybdenum concentrate sample, 1mL of hydrochloric acid, 2mL of nitric acid and 1mL of hydrofluoric acid were added to the molybdenum concentrate sample tube in sequence. 1mL of hydrochloric acid, 2mL of nitric acid and 1mL of hydrofluoric acid were added to the blank sample tube.

[0031] The molybdenum concentrate sample tube and the blank sample tube were subjected to microwave digestion. The carrier liquid used for microwave digestion included 150 mL of deionized water and 5 mL of nitric acid.

[0032] After digestion, place the sample on an acid-removing apparatus at 200℃ until the white fumes disappear. After cooling, add 5 mL of hydrochloric acid solution (1+1) and heat to dissolve on the acid-removing apparatus. After cooling again, dilute to 100 mL with deionized water to obtain the molybdenum concentrate sample solution and blank solution.

[0033] S2. Preparation of working curve solution:

[0034] Take 10.00 mL of potassium single-element standard stock solution with a mass concentration of 1000 μg / mL into a 100 mL volumetric flask, dilute with water to the mark, mix well, and obtain 1 mL of potassium standard solution containing 100 μg potassium.

[0035] Transfer 1 mL, 5 mL and 10 mL of the potassium standard solution into three 100 mL volumetric flasks within a 10 mL range. Take an empty 100 mL volumetric flask and add 10 mL of hydrochloric acid solution (1+1) to each of the four volumetric flasks. Dilute with water to the mark, mix well, and obtain a set of working curve solutions.

[0036] S3, Detection:

[0037] A set of working curve solutions of S2 were placed on an inductively coupled plasma atomic emission spectrometer to measure the spectral intensity of potassium, thus obtaining a standard working curve starting from the blank value.

[0038] The molybdenum concentrate sample solution and blank solution from S1 are placed on an ion emission spectrometer. After subtracting the blank value, the percentage content of potassium in the sample solution is determined from the standard working curve.

[0039] Step S1 is the sample processing stage. In this stage, the mass of the molybdenum concentrate sample in this embodiment is weighed from 0.1000g to 0.1500g, accurate to 0.0001g, and placed in a polytetrafluoroethylene (PTFE) digestion tube. 1ml of hydrochloric acid, 2ml of nitric acid, and 1ml of hydrofluoric acid are added and mixed to dissolve the sample. Simultaneously, the same type and volume of acid are added to another empty PTFE digestion tube as a blank control. Thus, there are two sample tubes: a molybdenum concentrate sample tube and a blank sample tube.

[0040] Subsequently, all digestion tubes containing samples and blank controls were placed in a microwave digester and digested according to a preset program. The pre-pressure setting for microwave digestion was 3-5 MPa, the maximum temperature was set to 180℃-220℃, and the holding time was set to 10-20 minutes. In this embodiment, the preferred pre-pressure setting was 4 MPa, the temperature was controlled at 200℃, and the holding time was 15 minutes. The carrier solution consisted of 150 ml of deionized water and 5 ml of nitric acid. After digestion, the digestion tubes were removed and placed on an acid-removing apparatus. Acid was removed at 200℃ until the white fumes completely evaporated, and then cooled to room temperature. Then, 5 ml of hydrochloric acid solution (1+1) was added and heated to dissolve on the acid-removing apparatus. It is necessary to ensure that the residue on the digestion tube walls is thoroughly cleaned; therefore, the digestion tube walls can be rinsed before heating to dissolve on the acid-removing apparatus. After cooling, the volume was adjusted to 100 ml with deionized water to obtain the molybdenum concentrate sample solution and the blank solution.

[0041] In some preferred embodiments, the mass range of the molybdenum concentrate sample is preferably from 0.1200 g to 0.1400 g to ensure a suitable sample amount for subsequent digestion and volume adjustment. The hydrochloric acid solution (1+1) used in the digestion process can be prepared by diluting concentrated hydrochloric acid, specifically in a volume ratio of concentrated hydrochloric acid to deionized water of 1:1.

[0042] Step S2 is the preparation stage of the working curve solutions. In this stage, 10.00 ml of potassium single-element standard stock solution with a concentration of 1000 μg / ml is transferred to a 100 ml volumetric flask, diluted with water to the mark, and mixed well to obtain a potassium standard solution with a concentration of 100 μg / ml. Based on this, 1 ml, 5 ml, and 10 ml of the above potassium standard solution are transferred to three 100 ml volumetric flasks respectively, and 10 ml of hydrochloric acid solution (1+1) is added to each volumetric flask. The solutions are then diluted with water to the mark and mixed well to form a series of working curve solutions with different concentration gradients. In addition, another 100 ml empty volumetric flask is taken, and 10 ml of (1+1) hydrochloric acid solution is added. The solutions are then diluted with water to the mark and mixed well to serve as a blank working curve solution.

[0043] In some implementations, the concentration range of the potassium standard solution can be adjusted from 50 μg / ml to 150 μg / ml as needed to meet calibration requirements with different concentration gradients. The concentration gradient of the working curve solution can be extended to 0.5 ml, 2 ml, 6 ml, and 10 ml of potassium standard solution to further refine the detection range and improve calibration accuracy.

[0044] Step S3 is the detection stage. In this stage, inductively coupled plasma atomic emission spectrometry (ICP-AES) is used to measure the solutions of the working curves. The radio frequency power is set to 1200 W, the auxiliary gas flow rate is 1.0 L / min, the sample flow rate range is 1.0~5.0 mL / min, the characteristic spectral line of potassium is selected at 766.491 nm, and the argon purity is not less than 99.99%. By measuring the spectral intensity of potassium in each working curve solution, a standard working curve starting from the blank value is plotted. Subsequently, the molybdenum concentrate sample solution and the blank solution prepared in step S1 are sequentially placed in the ICP-AES for measurement. After subtracting the blank value, the percentage content of potassium in the sample solution is determined according to the standard working curve.

[0045] In some implementations, the radio frequency power of the inductively coupled plasma atomic emission spectrometer can be adjusted from 1000W to 1500W, the auxiliary gas flow rate from 0.8L / min to 1.2L / min, and the sample flow rate from 0.5mL / min to 6.0mL / min to accommodate different instrument models and experimental conditions. The characteristic spectral lines for potassium can also be selected at 404.414nm or 404.721nm to address potential interference signals under specific conditions.

[0046] Preferably, the embodiments of this application further include repeatability testing: two molybdenum concentrate samples from different sources are selected and labeled as molybdenum concentrate sample No. 1 and molybdenum concentrate sample No. 2, respectively. The measurements are repeated multiple times according to steps S1-S3, and the results of each measurement are recorded and the average value and relative standard deviation are calculated.

[0047] Meanwhile, the embodiments of this application also include the following steps: after the sample solution prepared in step S1 is cooled, a certain amount of potassium standard solution is added, and the sample is re-measured according to steps S2 and S3 to calculate the spiked recovery rate.

[0048] According to this application, the above method completely releases potassium from molybdenum concentrate samples and introduces it into the solution system through acid digestion and microwave treatment, avoiding the complex matrix separation process in traditional methods. Simultaneously, the introduction of hydrochloric acid solution (1+1) for subsequent processing of the sample solution further suppresses matrix interference and improves the accuracy of the detection results. Furthermore, the use of inductively coupled plasma atomic emission spectrometry (ICP-AES) for high-sensitivity potassium detection significantly reduces the detection limit and improves the spiked recovery rate, meeting the demand for efficient and rapid detection of potassium content in molybdenum concentrate in actual production.

[0049] The method for detecting potassium content in molybdenum concentrate according to any embodiment of the first aspect has the characteristics of high sensitivity, high accuracy and high repeatability, and is suitable for the rapid quality monitoring needs in molybdenum concentrate production. It can also meet the requirements of the molybdenum metal smelting industry for detecting potassium content in raw materials.

[0050] In some implementations, this method can be applied to the batch testing of multiple molybdenum concentrate samples. By optimizing the sample pretreatment process and instrument parameter settings, it can achieve a daily testing capacity of more than 50 samples, significantly improving testing efficiency. In other implementations, this method can be further combined with automated equipment, such as autosamplers and sample processing workstations, to reduce manual intervention and improve testing consistency.

[0051] This method can be extended to the detection of other potassium-containing minerals, such as potassium feldspar and mica, by appropriately adjusting sample processing steps and instrument parameters to achieve a wider range of applications. Furthermore, this method can be coupled with other elemental detection techniques, such as inductively coupled plasma mass spectrometry (ICP-MS) to simultaneously determine the content of multiple trace elements in molybdenum concentrate, thereby comprehensively assessing sample quality.

[0052] In some implementations, this method can be combined with an online monitoring system to collect real-time data on changes in potassium content during the production of molybdenum concentrate, providing a scientific basis for enterprise production decisions.

[0053] The following are specific embodiments.

[0054] Example 1

[0055] Two molybdenum concentrate samples were taken and labeled as molybdenum concentrate sample 1 and molybdenum concentrate sample 2, respectively. The same molybdenum concentrate sample was measured 7 times according to the steps and methods in this embodiment. The percentage content of potassium in molybdenum concentrate sample 1 and molybdenum concentrate sample 2 is shown in Table 1 below.

[0056] Table 1 shows the results of potassium content determination in samples #1 and #2 of molybdenum concentrate.

[0057] Sample number 1 time 2 times 3 times 4 times 5 times 6 times 7 times average value / % RSD / % 1# 0.33 0.32 0.33 0.33 0.32 0.33 0.33 0.33 1.75 2# 0.24 0.24 0.23 0.24 0.24 0.24 0.23 0.24 2.41

[0058] As can be seen from Table 1, the relative standard deviation (RSD) of the measurement results is less than 5%, indicating that the detection method of the present invention has good precision and stability.

[0059] Example 2

[0060] To determine the potassium spiked recovery rate of molybdenum concentrate samples #1 and #2, the sample solution in S1 was cooled and transferred to a 100mL volumetric flask, and a certain amount of potassium standard solution was added. The remaining analysis was performed according to the procedure in this embodiment. The spiked recovery rate of the sample was the ratio of the difference between the measured result after adding the potassium standard solution and the original content of the sample, and the theoretical value of the added standard solution. That is, potassium spiked recovery rate = (total potassium content in the sample - original potassium content in the sample). The amount of potassium standard added is multiplied by 100%; the determination results are shown in Table 2.

[0061] Table 2 Measurement Results

[0062] Sample number Original potassium content in the sample / mg Volume of potassium standard solution added (mg) Potassium content measured / mg Potassium spiked recovery rate / % 1# 0.33 1.0 1.34 101 2# 0.24 1.0 1.23 99

[0063] As shown in Table 2, the spiked recoveries were all above 95%, indicating that the present invention has good accuracy.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for detecting potassium content in molybdenum concentrate, characterized in that, The method includes the following steps: S1. Preparation of molybdenum concentrate sample solution and blank solution: Two polytetrafluoroethylene digestion tubes were used as a molybdenum concentrate sample tube and a blank sample tube, respectively. 0.1000~0.1500g of molybdenum concentrate sample, 1mL of hydrochloric acid, 2mL of nitric acid and 1mL of hydrofluoric acid were added to the molybdenum concentrate sample tube in sequence. 1mL of hydrochloric acid, 2mL of nitric acid and 1mL of hydrofluoric acid were added to the blank sample tube. The molybdenum concentrate sample tube and the blank sample tube were subjected to microwave digestion. The carrier liquid used for microwave digestion included 150 mL of deionized water and 5 mL of nitric acid. After digestion, place the sample on an acid-removing apparatus at 200℃ until the white fumes disappear. After cooling, add 5 mL of hydrochloric acid solution (1+1) and heat to dissolve on the acid-removing apparatus. After cooling again, dilute to 100 mL with deionized water to obtain the molybdenum concentrate sample solution and blank solution. S2. Preparation of working curve solution: Take 10.00 mL of potassium single-element standard stock solution with a mass concentration of 1000 μg / mL into a 100 mL volumetric flask, dilute with water to the mark, mix well, and obtain 1 mL of potassium standard solution containing 100 μg potassium. Transfer 1 mL, 5 mL and 10 mL of the potassium standard solution into three 100 mL volumetric flasks within a 10 mL range. Take an empty 100 mL volumetric flask and add 10 mL of hydrochloric acid solution (1+1) to each of the four volumetric flasks. Dilute with water to the mark, mix well, and obtain a set of working curve solutions. S3, Detection: A set of working curve solutions of S2 were placed on an inductively coupled plasma atomic emission spectrometer to measure the spectral intensity of potassium, thus obtaining a standard working curve starting from the blank value. The molybdenum concentrate sample solution and blank solution from S1 are placed on an ion emission spectrometer. After subtracting the blank value, the percentage content of potassium in the sample solution is determined from the standard working curve.

2. The method for detecting potassium content in molybdenum concentrate according to claim 1, characterized in that, The acid reagents used in microwave digestion are hydrochloric acid, nitric acid, and hydrofluoric acid, with a volume ratio of 1:2:

1.

3. The method for detecting potassium content in molybdenum concentrate according to claim 1, characterized in that, The pre-pressurization setting for microwave digestion is 3 MPa-5 MPa, the maximum temperature setting is 180℃-220℃, and the holding time setting is 10 min-20 min.

4. The method for detecting potassium content in molybdenum concentrate according to claim 3, characterized in that, The microwave digestion pre-pressurization was set to 4 MPa, the maximum temperature was set to 200℃, and the holding time was set to 15 min.

5. The method for detecting potassium content in molybdenum concentrate according to claim 1, characterized in that, In step S1, the digestion tube wall is rinsed before heating and dissolving on the acid-removing apparatus.

6. The method for detecting potassium content in molybdenum concentrate according to claim 1, characterized in that, The inductively coupled plasma atomic emission spectrometer was set to 1200 W RF power, 1.0 L / min auxiliary gas flow rate, 1.0-5.0 mL / min sample flow rate, 766.491 nm potassium spectral line, and ≥99.99% argon purity.

7. The method for detecting potassium content in molybdenum concentrate according to claim 1, characterized in that, The procedure also includes the following steps: Select two molybdenum concentrate samples from different sources, label them as molybdenum concentrate sample No. 1 and molybdenum concentrate sample No. 2, and perform repeated measurements multiple times according to steps S1-S3. Record the results of each measurement and calculate the average value and relative standard deviation.

8. The method for detecting potassium content in molybdenum concentrate according to claim 1, characterized in that, The method also includes the following steps: after the sample solution prepared in step S1 is cooled, a certain amount of potassium standard solution is added, and the sample is re-measured according to steps S2 and S3 to calculate the spiked recovery rate.