Method for measuring concentration of flocculant during counter-current decantation (CCD) washing of lateritic nickel ore

Abstract

The present application relates to a method for measuring the concentration of a flocculant during CCD washing of lateritic nickel ore. The method comprises the following steps: determining the solid content C1 of a flocculant by means of a drying method, wherein the flocculant is polyacrylamide; adding the flocculant to industrial water, mixing same until uniform, leaving same to stand, taking the supernatant as a flocculant solution, measuring the water content C2 of the flocculant solution, obtaining the content C3 of total dissolved solids in the industrial water, and obtaining the flocculant content C4 of the flocculant solution on the basis of the water content and the content of the total dissolved solids; and obtaining the concentration of the flocculant on the basis of the solid content C1 of the flocculant and the flocculant content C4 of the flocculant solution. In the present application, the water content of the flocculant solution is measured, and then the flocculant content of the flocculant solution is obtained on the basis of the water content and the content of total dissolved solids; and the method is not affected by changes in the molecular weight of a polymer and the degree of hydrolysis, can accurately measure the mass concentration of the flocculant in the flocculant solution, has the characteristic of high accuracy, and meets the requirements of field measurement.

Description

Method for detecting flocculant concentration in counter-current washing of laterite nickel ore CCD TECHNICAL FIELD

[0001] The present application relates to the field of hydrometallurgy, in particular to a method for detecting flocculant concentration in counter-current washing of laterite nickel ore CCD. BACKGROUND

[0002] In the process of preparing nickel-cobalt hydroxide (MHP) from laterite nickel ore, which includes high-pressure acid leaching, cyclic leaching, pre-neutralization, CCD counter-current washing, iron and aluminum removal, and nickel-cobalt precipitation steps in sequence, polyacrylamide (PAM) plays multiple important roles: (1) flocculation: PAM can aggregate fine mineral particles into larger floccules through adsorption and bridging, facilitating sedimentation and separation, and thus improving metal recovery; (2) increasing solution viscosity: PAM can increase the viscosity of the solution, improving the flowability and stability of the slurry, preventing stratification and precipitation, which is very important for maintaining the uniformity of the slurry; (3) improving filtration efficiency: during filtration, PAM can improve filtration efficiency and reduce water content in the filter cake, thereby improving metal recovery; (4) promoting contact: PAM can also promote the contact between leaching agent and mineral surface, improving leaching efficiency and metal recovery.

[0003] PAM plays a very important role in the hydrometallurgical process of laterite nickel ore. In order to ensure the best flocculation effect and metal recovery, the concentration of PAM needs to be accurately controlled. If the concentration of PAM is too low, it cannot fully neutralize the charge of suspended particles or form enough adsorption bridges, resulting in unsatisfactory flocculation effect, making it difficult for particles to effectively aggregate and settle. Moreover, due to the poor flocculation effect, the solid-liquid separation process may take longer, affecting the processing efficiency. If the concentration of PAM is too high, it may have the following disadvantages: (1) increased viscosity: high-concentration PAM solution has high viscosity, which may lead to uneven mixing and affect the flocculation effect; (2) increased cost: using high-concentration PAM increases reagent cost, especially in large-scale processing, this cost increase may be very significant; (3) increased burden on processing equipment: high-viscosity PAM solution may cause greater burden on processing equipment, increasing equipment wear and maintenance cost; (4) increased side effects: high-concentration PAM may not fully hydrolyze, affecting the flocculation effect, and even may produce side effects.

[0004] In the process of preparing PAM solution as a flocculant in the CCD counter-current washing, industrial water is used as the solvent (using pure water is too expensive for industrial production), and the industrial water usually contains suspended solids and total dissolved solids. When the flocculant is added to the industrial water, it will flocculate the suspended solids and total dissolved solids, resulting in a small amount of gel precipitation. In actual use, the supernatant is used as the flocculant solution. However, the flocculation precipitation will cause the loss of the flocculant, so the actual concentration of the flocculant in the supernatant cannot be calculated by the solid mass / liquid volume method, and the concentration of the flocculant in the supernatant used actually needs to be accurately detected. The commonly used methods for detecting the concentration of PAM in water currently mainly include ultraviolet-visible spectroscopy (UV-Vis), mass spectrometry, ion chromatography, solution polymer detection method, and viscosity measurement method, etc.:

[0005] Ultraviolet-visible spectroscopy (UV-Vis): This method uses an infrared spectrometer to measure the absorption spectrum of the sample in the infrared region, and determines the content of PAM by judging the position and intensity of the absorption peak. The advantages are simple operation, fast, and can simultaneously detect multiple organic substances. The disadvantage is that it requires high purity, and needs special equipment and standard products for quantitative analysis.

[0006] Mass spectrometry: Mass spectrometry is a method based on mass spectrometer to measure the mass and relative abundance of various ions or molecules in the sample. This method is suitable for complex sample matrices and can accurately analyze the structure and content of polyacrylamide. However, the equipment and operation cost of this method is high, and the requirement for operators is also high.

[0007] Ion chromatography: Ion chromatography is a method that uses a chromatographic column to separate the components in the sample, and then uses a detector to quantitatively analyze the separated polyacrylamide. This method can be used to analyze complex sample matrices and can simultaneously detect multiple organic substances. The advantages of this method are high sensitivity and good selectivity, but it requires a professional operator and more complex instrument equipment.

[0008] Solution polymer detection method: This method reacts the sample to be tested with a specific reagent to generate a quantifiable product, and then determines it by colorimetry, spectrophotometry, etc. The advantages of this method are simple operation, low cost, and can be used for large-scale analysis. However, this method has high requirements for sample pretreatment and is not suitable for all types of samples.

[0009] Viscosity measurement method: the principle of this method is based on the known correspondence between the viscosity and concentration of polymer under certain shear conditions, the concentration is obtained by measuring the viscosity of the sample. Viscosity method requires that the viscosity and concentration of PAM solution be proportional to the change, only can be used for known component of pure system. Molecular weight, degree of hydrolysis, temperature, ionic strength, pH and shear rate will affect the viscosity of PAM solution, so that the method is greatly limited in practical application.

[0010] Therefore, the above detection method has the disadvantages of high requirement for sample purity and operator, expensive equipment, etc., and cannot meet the rapid and convenient detection requirement, so it is necessary to develop a convenient, fast and accurate PAM detection method.

[0011] SUMMARY

[0012] The purpose of the present application is to overcome the above technical deficiencies, provide a method for detecting the concentration of flocculant in the countercurrent washing of laterite nickel ore CCD, and solve the technical problem that the actual concentration of flocculant is difficult to determine quickly and accurately in the prior art.

[0013] To achieve the above technical purpose, the technical scheme provided by the present application is:

[0014] In a first aspect, the present application provides a method for detecting the concentration of flocculant in the countercurrent washing of laterite nickel ore CCD, comprising the following steps:

[0015] The drying method is used to determine the solid content C1 of the flocculant; the flocculant is polyacrylamide;

[0016] The flocculant is added to industrial water and mixed uniformly, and the supernatant is taken as the flocculant solution after standing, the moisture content C2 of the flocculant solution is determined, and the total dissolved solids content C3 in the industrial water is obtained, and the flocculant content C4 of the flocculant solution is obtained according to the moisture content and the total dissolved solids content;

[0017] The flocculant concentration is obtained according to the flocculant solid content C1 and the flocculant content C4 of the flocculant solution.

[0018] Preferably, in the drying method, the flocculant is dried at 115-125 DEG C to constant weight.

[0019] Further preferably, the drying time is 1.5-2.5 h.

[0020] Preferably, the mass fraction of the flocculant added to the industrial water is 0.1%-1%.

[0021] Preferably, the moisture content of the flocculant solution is determined by a rapid moisture meter.

[0022] Further preferably, the rapid moisture meter is a Mettler rapid moisture meter HX204.

[0023] Preferably, the flocculant concentration C = C4 / C1 x 100%.

[0024] Further preferably, C4 = 1-C2-C3.

[0025] Preferably, the step of obtaining the total dissolved solids content in the industrial water specifically comprises: determining the total dissolved solids content in the industrial water by the drying method after filtering the industrial water.

[0026] Compared with the prior art, the beneficial effects of the present application include:

[0027] In the present application, the flocculant content of the flocculant solution is determined by measuring the moisture content of the flocculant solution, and the flocculant content of the flocculant solution is obtained according to the moisture content and the total dissolved solids content in the industrial water, which is not affected by the molecular weight change and the degree of hydrolysis of the polymer, can accurately determine the mass concentration of the flocculant in the flocculant solution, has the characteristics of high accuracy, meets the requirements of on-site detection, and solves the problem of large detection error of the flocculant concentration in the flocculant solution at present. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is the detection result of Example 1 of the present application;

[0029] Figure 2 is the detection result of Example 2 of the present application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0031] The concentration of polyacrylamide (PAM) in water treatment is a key parameter, ensuring its correct dosage not only can improve the efficiency in hydrometallurgy, but also can ensure safety and economic benefits; but a small amount of gel precipitate is produced during the preparation of PAM solution, which causes the loss of flocculant, resulting in that the actual concentration of the flocculant is not accurate according to the calculated value of solid mass / liquid volume, and other detection methods usually require precision instruments, which are expensive and require high skilled operators, and have high cost, therefore a simple method is needed to accurately detect the flocculant concentration, the flocculant concentration in the present application refers to the actual feeding ratio of the flocculant in the flocculant solution prepared by industrial water.

[0032] In a first aspect, the present application provides a method for detecting the concentration of flocculant in the countercurrent washing of laterite nickel ore CCD, comprising the following steps:

[0033] The drying method is used to determine the solid content C1 of the flocculant; the flocculant is polyacrylamide;

[0034] The flocculant is added into the industrial water and mixed uniformly, and the supernatant is taken as the flocculant solution after standing, the moisture content C2 of the flocculant solution is determined, and the total dissolved solid content C3 in the industrial water is obtained, and the flocculant content C4 of the flocculant solution is obtained according to the moisture content and the total dissolved solid content;

[0035] The flocculant concentration is obtained according to the flocculant solid content C1 and the flocculant content C4 of the flocculant solution.

[0036] In some embodiments, the flocculant is dried at 115-125°C to constant weight. PAM is dried at about 120°C and will not decompose, so drying to constant weight can obtain the solid content, which is simple and easy to implement.

[0037] Further preferably, the drying time is 1.5-2.5h; more preferably, 0.3-2g of the flocculant is weighed and dried at 115-125°C for 1.5-2.5h.

[0038] Preferably, the mass fraction of the flocculant added into the industrial water is 0.1%-1%.

[0039] Preferably, the moisture content of the flocculant solution is determined by a rapid moisture meter. During each determination, about 5-30g of the flocculant solution is weighed and tested for moisture content by the rapid moisture meter.

[0040] Further preferably, the rapid moisture meter is a Mettler rapid moisture meter HX204.

[0041] Preferably, the industrial water includes water treated by preliminary sedimentation from rivers or lakes, which contains suspended solids and salts; the flocculant concentration C=C4 / C1x100%.

[0042] The flocculant is usually prepared with industrial water in production, but the industrial water contains suspended solids and has a high total dissolved solid content. For example, obvious suspended solids can be found in the industrial water in the workshop, while the PAM flocculant solution taken from the workshop storage tank is clear. Considering that the industrial water contains many impurities and has high salt content, it is necessary to exclude the influence of suspended solids and total dissolved solids to accurately determine the concentration of the supernatant flocculant.

[0043] Further preferably, when the water is industrial water, the total dissolved solid content C3 in the filtered industrial water is obtained first, and C4=1-C2-C3, i.e. the flocculant concentration=(1-C2-C3) / C1x100%. Since the industrial water also contains dissolved solids (such as salts), it will also cause deviation of the flocculant concentration, so the total dissolved solid content C4 in the filtered industrial water is determined first to reduce interference and obtain the accurate actual flocculant concentration.

[0044] Preferably, the step of obtaining the total dissolved solids content of the industrial water specifically comprises: filtering the industrial water and then determining the total dissolved solids content by the drying method.

[0045] Further preferably, the industrial water is filtered by filter paper or filter cloth.

[0046] The advantages of the present application are:

[0047] (1) The detection method of the flocculant concentration of the present application has the characteristics of simple method, high accuracy, etc.

[0048] (2) The present application can obtain the moisture content of the prepared flocculant solution in a short time by using the rapid moisture meter, so as to obtain the flocculant content of the flocculant solution, and the actual flocculant concentration can be quickly determined in combination with the flocculant solid content.

[0049] (3) The present application method is not affected by the molecular weight change and the hydrolysis degree of the polymer, and can accurately determine the mass concentration of the flocculant in the flocculant solution, has high accuracy, meets the requirements of on-site detection, solves the problem of large detection error of the mass concentration of the flocculant in the flocculant solution at present, and has certain popularization and application prospect.

[0050] The present application will be further described in detail below through specific examples.

[0051] Example 1 (feasibility verification)

[0052] In order to verify the feasibility of the present application, desalted water (without the influence of suspended matter and dissolved solids) is used to prepare the flocculant solution; when the desalted water is used, C4 = 1-C2, that is, the flocculant concentration = (1-C2) / C1 x 100%. In the present application, the flocculant content is obtained as 1-C2 according to the moisture content C2 of the flocculant solution, and the feeding ratio is inversely deduced by the ratio of the flocculant content (1-C2) to the flocculant solid content C1, that is, the actual flocculant concentration can be obtained; specifically comprising the following steps:

[0053] S1, first test the solid content C1 of PAM, weigh about 1g of PAM, dry at 120℃ for 2h, and then weigh, and the specific test results are shown in Table 1.

[0054] Table 1 Solid content of PAM

[0055] The average value of the two groups of results in Table 1 is determined to be the solid content of PAM, which is 92.61%.

[0056] S2, add PAM into desalted water (laboratory pure water) to prepare flocculant solutions with mass concentrations of 0.1%, 0.2%, 0.3%, 0.4% and 0.5% respectively, take 20g of the flocculant solution to test the moisture content C2 by using a rapid moisture meter, then obtain the flocculant content C4 of the flocculant solution according to the moisture content, C4 = 1-C2, and calculate the actual flocculant concentration C = C4 / C1*100%, wherein the flocculant concentration is prepared twice for each concentration; and take the flocculant concentration calculated by the PAM preparation concentration*the solid content of PAM as a control group 1, and the results are shown in Table 2 and Figure 1.

[0057] Table 2: Flocculant solution concentration prepared with desalted water

[0058] As can be seen from Table 2 and Figure 1, the actual flocculant concentration C obtained by the method of the present application is close to the PAM preparation concentration, which indicates that the method of the present application is feasible.

[0059] Example 2

[0060] A detection method of flocculant concentration in a CCD countercurrent washing of a laterite nickel ore, comprising the following steps:

[0061] S1, same as step S1 of Example 1;

[0062] S2, filter the industrial water with filter paper, and then determine the total dissolved solids content C3 in the industrial water by using the drying method; prepare a mixture with mass concentrations of 0.2%, 0.3% and 0.4% by using industrial water and PAM respectively, take the supernatant as a flocculant solution after standing, take 20g of the flocculant solution to test the moisture content C2 by using a rapid moisture meter, then obtain the total solids content 1-C2 of the flocculant solution according to the moisture content, and deduct the influence of the total dissolved solids to obtain the PAM content C4 = 1-C2-C3 of the flocculant solution, and then calculate the actual flocculant concentration C = C4 / C1*100%; and obtain the flocculant solution concentration by the viscosity method based on the Chinese national standard GB-T12088, to compare with a control group 2; take the flocculant solution used in the CCD countercurrent washing production line of the laterite nickel ore (referred to as production line sample) for synchronous determination, and the results are shown in Table 3 and Figure 2.

[0063] Table 3: Flocculant solution concentration prepared with industrial water

[0064] As can be seen from Table 3 and Figure 2, after removing the influence of the total dissolved solids (such as salt) of the industrial water, the actual flocculant concentration C obtained is close to the result of the control group 2, and the test is accurate.

[0065] The specific implementation of the present application described above does not constitute a limitation on the protection scope of the present application. Any various other corresponding changes and modifications made according to the technical concept of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for detecting the concentration of flocculants in the countercurrent washing of laterite nickel ore, comprising the following steps: determining the solid content of the flocculants C1 by drying method; the flocculants are polyacrylamide; adding the flocculants to industrial water and mixing uniformly, then taking the supernatant after standing as the flocculant solution, determining the moisture content C2 of the flocculant solution, and obtaining the total dissolved solids content C3 in the industrial water, and obtaining the flocculant content C4 of the flocculant solution according to the moisture content and the total dissolved solids content; obtaining the flocculant concentration according to the flocculant solid content C1 and the flocculant content C4 of the flocculant solution.

2. The method for detecting flocculant concentration in a laterite nickel ore CCD counter-current washing according to claim 1, characterized in that, In the drying method, the flocculants are dried to constant weight at 115-125℃.

3. The method for detecting flocculant concentration in a laterite nickel ore CCD counter-current washing according to claim 2, characterized in that, The drying time is 1.5-2.5h.

4. The method for detecting flocculant concentration in a laterite nickel ore CCD counter-current washing according to claim 1, characterized in that, The mass fraction of the flocculants added to the industrial water is 0.1%-1%.

5. The method for detecting flocculant concentration in a laterite nickel ore CCD counter-current washing according to claim 1, characterized in that, The moisture content of the flocculant solution is determined by a rapid moisture meter.

6. The method for detecting flocculant concentration in a laterite nickel ore CCD counter-current washing according to claim 5, characterized in that, The rapid moisture meter is a Mettler rapid moisture meter HX204.

7. The method for detecting flocculant concentration in a laterite nickel ore CCD counter-current washing according to claim 1, characterized in that, The flocculant concentration C=C4 / C1×100%.

8. The method for detecting flocculant concentration in a laterite nickel ore CCD counter-current washing according to claim 7, characterized in that, The flocculant content C4 of the flocculant solution=1-C2-C3.

9. The method for detecting flocculant concentration in a laterite nickel ore CCD counter-current washing according to claim 1, characterized in that, The step of obtaining the total dissolved solids content in the industrial water specifically comprises: filtering the industrial water, and then determining the total dissolved solids content by drying method.

10. The method for detecting flocculant concentration in a lateritic nickel ore CCD counter-current washing according to claim 9, characterized in that, The industrial water is filtered by filter paper or filter cloth.

Images