Method for determining tin content in polymetallic ore by alkali-salicylic acid-hydrofluoric acid complexing
By treating ore samples using an alkaline dissolution-hydrochloric acid-hydrofluoric acid acidification complexation method, combined with ICP-OES determination of tin content, the problem of inaccurate tin determination results in complex matrices was solved, achieving high recovery rate and high precision tin analysis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SICHUAN XIYE GEOLOGY TESTING TECH CO LTD
- Filing Date
- 2026-06-23
- Publication Date
- 2026-07-28
AI Technical Summary
Existing technologies suffer from severe interference when determining tin in complex matrices (high phosphorus, high aluminum, high silicon, niobium-tantalum), resulting in low tin recovery rates and inaccurate results.
The alkali-hydrochloric acid-hydrofluoric acid acidification complexation method was adopted. After the ore sample was melted and decomposed with sodium peroxide, a mixture of hydrochloric acid and hydrofluoric acid was added to form a soluble fluorine complex. The tin content was determined by full-spectrum direct-reading inductively coupled plasma optical emission spectrometry (ICP-OES).
It effectively eliminates matrix interference, increases tin recovery to 101%~105%, and has a relative standard deviation of less than 0.57%. The results are accurate and reliable, and it is suitable for rapid analysis of complex geological samples.
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Figure CN122468698A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of ore analysis and testing technology, specifically relating to a method for determining the tin content in polymetallic ores using alkali dissolution-hydrochloric acid-hydrofluoric acid acidification complexation. Background Technology
[0002] Tin is a strategic metallic resource, and its accurate determination is crucial in geological exploration, ore beneficiation, and product quality control. Phosphate-lithium-aluminate polymetallic ores often contain high levels of phosphorus, aluminum, and silicon, and coexist with high field strength elements such as niobium and tantalum. This complex matrix significantly interferes with the quantitative analysis of tin. Traditional analytical methods often employ acidification in sulfuric acid media, polarography, or potassium iodate titration, but these methods have significant limitations in practical applications.
[0003] In sulfuric acid systems, silicon readily hydrolyzes to form silicate colloids, aluminum hydrolyzes to form aluminum hydroxide, and phosphorus exists as phosphate ions. These three elements synergistically form a high specific surface area composite colloid, which strongly adsorbs, encapsulates, and co-precipitates tetravalent tin, leading to significant tin loss. Simultaneously, niobium and tantalum readily hydrolyze under weakly acidic conditions to form insoluble oxides, further exacerbating matrix interference and resulting in systematically low and poorly repeatable measurement results. Furthermore, conventional wet decomposition methods struggle to completely open the crystal lattices of silicates and niobium-tantalum minerals, resulting in incomplete tin dissolution and a recovery rate of only 70-80%, failing to meet the precise detection requirements for complex ores with high phosphorus, high aluminum, and high silicon content. Summary of the Invention
[0004] In view of the above-mentioned prior art, the present invention discloses a method for determining the tin content in polymetallic ores by alkaline dissolution-hydrochloric acid-hydrofluoric acid acidification complexation, so as to solve the technical problem that complex matrices (high phosphorus, high aluminum, high silicon, niobium and tantalum) interfere with the determination of tin, resulting in low tin recovery rate and inaccurate results.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for determining the tin content in polymetallic ores using alkali dissolution-hydrochloric acid-hydrofluoric acid acidification complexation, comprising the following steps: Sample pretreatment: Place the ore sample in a container, add sodium peroxide, stir evenly, and then cover with another layer of sodium peroxide. Melt and decompose at 720~740℃. After cooling, add water at 80~90℃ to extract the melt. After further cooling, add a mixed acid of hydrochloric acid and hydrofluoric acid. Make up the volume of the resulting mixed solution, shake well, and let stand. Take the supernatant and dilute it with aqua regia with a volume fraction of 5~10% to obtain the test solution; the volume fraction of hydrofluoric acid in the mixed acid is 0.3~0.6%. Determination: A standard curve was established and the characteristic spectral lines of tin in the test solution were determined using a full-spectrum direct-reading inductively coupled plasma atomic emission spectrometer. The tin content in the sample was calculated based on the standard curve.
[0006] Based on the above technical solution, the present invention can be further improved as follows: Furthermore, the elemental composition of the ore sample includes phosphorus, aluminum, silicon, niobium, and tantalum.
[0007] Furthermore, the mass ratio of ore sample to total sodium peroxide was 0.1~0.5:3~5.
[0008] Furthermore, the melting time is 8~12 minutes.
[0009] Furthermore, the volume fraction of hydrofluoric acid in the mixed acid is 0.5%.
[0010] Furthermore, the ratio of ore sample, water, and mixed acid is 0.1~0.5g: 50~70mL: 15~20mL.
[0011] Furthermore, the dilution factor of the supernatant diluted with aqua regia with a volume fraction of 5-10% is 18-22 times, preferably 20 times.
[0012] Furthermore, the operating parameters of the full-spectrum direct-reading inductively coupled plasma atomic emission spectrometer are as follows: power of 1.0-1.25kW, plasma gas flow rate of 12.0-16.0L / min, measurement wavelength of 189.925nm, auxiliary gas flow rate of 1.00-2.00L / min, observation height of 7-9mm, nebulizing gas flow rate of 0.5-1.0L / min, and reading time of 5-7s, radial observation; the preferred parameters are: power of 1.2kW, plasma gas flow rate of 15.0L / min, measurement wavelength of 189.925nm, auxiliary gas flow rate of 2.00L / min, observation height of 8mm, nebulizing gas flow rate of 0.70L / min, and reading time of 5s, radial observation.
[0013] Furthermore, the formula for calculating tin content is:
[0014] in To determine the tin concentration (mg / L) in the solution, This is the final volume (mL) after dilution. To measure the volume (mL), V 0 represents the initial final volume (mL). The mass of the sample is (g).
[0015] The beneficial effects of this invention are: 1. Effectively eliminate matrix interference: Through acidification and complexation using a hydrochloric acid-hydrofluoric acid system, easily hydrolyzed elements such as silicon, aluminum, niobium, and tantalum are converted into soluble fluorine complexes, inhibiting colloid formation and preventing tin from being adsorbed or encapsulated and lost.
[0016] 2. The test results are accurate and reliable: compared with the potassium iodate titration method, the results meet the requirements of the "Quality Management Standard for Geological and Mineral Laboratory Testing". The spiked recovery rate is 101%~105%, and the relative standard deviation (RSD, n=6) is 0.57%.
[0017] 3. Simple and efficient operation: The sample pretreatment steps are simple, and combined with ICP-OES, it is suitable for rapid and accurate analysis of tin in complex geological samples (such as high phosphorus, high aluminum, and niobium-tantalum ore samples). Attached Figure Description
[0018] Figure 1 The working curve for determining tin by inductively coupled plasma atomic emission spectrometry. Detailed Implementation
[0019] The specific embodiments of the present invention will be described in detail below with reference to examples.
[0020] I. Experimental Materials and Instruments Instrument: Full-spectrum direct-reading inductively coupled plasma spectrometer.
[0021] Reagents: Sodium peroxide (analytical grade); hydrochloric acid (ρ=1.19 g / mL), hydrofluoric acid (ρ=1.15 g / mL), deionized water (conductivity: 4.76 μs / cm).
[0022] Preparation of tin standard solution: Weigh 1.0000g of metallic tin (mass fraction >99.99%) and place it in a 1000mL volumetric flask. Add 200mL of hydrochloric acid and wait for it to completely dissolve (2~3 days). Dilute with water to the mark and shake well to obtain a tin standard solution with a concentration of 1mg / mL.
[0023] Samples: National Class I standard reference materials GBW07240, GBW07231 and GBW07232.
[0024] The raw ore sample used was spodumene. The raw ore sample was subjected to gravity separation to obtain tin concentrate and tin tailings; and subjected to strong magnetic separation to obtain niobium-tantalum concentrate. The results of the semi-quantitative spectral analysis of the raw ore sample are shown in Table 1.
[0025] Table 1. Semi-quantitative results of the spectra of raw ore samples (mass fraction, %)
[0026] Example 1: Sodium peroxide molten Hydrochloric acid + hydrofluoric acid acidification ICP OES method for determining tin content Sample pretreatment: Weigh 0.1~0.5g (accurate to 0.0001g) of raw ore, tin concentrate, tin tailings, and niobium-tantalum concentrate into a 25mL corundum crucible, add 3.5g of sodium peroxide, stir well, and then cover the surface with another layer of sodium peroxide; place in a muffle furnace at 730℃, and after the furnace temperature rises back to 730℃, keep it at that temperature for 10min to convert tin element into soluble stannate. After cooling, transfer the crucible and sample together into a 200mL beaker, add 60mL of 85℃ hot water to the beaker; after the solution cools slightly, add 18mL of hydrochloric acid-hydrofluoric acid mixed acid (HF volume fraction of 0.5%), stir thoroughly, wash the crucible with deionized water and remove it, cool, and dilute to a 100mL volumetric flask, shake well and let stand until insoluble matter settles; take the supernatant and dilute it 20 times with 6% aqua regia to obtain the test solution.
[0027] Spiked recovery experiment: Take raw ore and niobium-tantalum concentrate and standard substances, and use the same sample pretreatment method. The difference is that after adding hot water, 2 mL of tin standard solution with a concentration of 1 mg / mL is added. The rest of the steps are the same.
[0028] The tin standard solution was serially diluted to 1 μg / mL, 20 μg / mL, and 50 μg / mL using blank solution to prepare a standard curve as follows: Figure 1 As shown.
[0029] Tests and Results: The characteristic spectral lines of tin were determined by inductively coupled plasma atomic emission spectrometry, and the test results are shown in Table 2. At the same time, the potassium iodate titration method (GB / T15924-2010) was used for comparison and verification, and the results are shown in Table 3.
[0030] Table 2
[0031] Table 3
[0032] Compared with the potassium iodate titration method, the ICP-OES method of this invention has a higher sample recovery rate and more accurate and reliable determination results.
[0033] Example 2 Methodological Validation An external standard method was used to establish a Sn standard curve. The recovery rate of tin spiked samples was 95-102%, and the relative standard deviation (RSD) of the standard sample determination was <2%. Compared with the potassium iodate titration method, the pretreatment ICP-OES coupling method of this invention has good stability, high repeatability, and accurate detection results.
[0034] Example 3: Matrix Interference Mechanism and Verification with Actual Mineral Samples Potassium dihydrogen phosphate and spectrally pure quartz were weighed separately, melted with sodium oxide at 720℃, and then tin, aluminum, niobium and tantalum standard solutions were added. After acidification with sulfuric acid, single-factor and multi-factor simulation experiments were carried out in accordance with the polarographic analysis procedure in Chapter 48 of the third volume of the fourth edition of "Rock and Mineral Analysis". The results are shown in Table 4.
[0035] Table 4
[0036] Mechanism analysis: 1. Interference from phosphorus: In sulfuric acid medium, phosphorus exists as PO4. 3- Existence, PO4 3- With Sn 4+ The formation of stable coordination complexes leads to the free Sn in the solution 4+ As the concentration decreases, the polarographic signal decreases because it measures the reducible state of Sn. This method involves the addition of barium chloride, which produces barium sulfate precipitate. However, in a high-phosphorus system, phosphorus adsorbs onto the barium sulfate surface, preventing Sn from precipitating. 4+ Phosphorus will be adsorbed together, leading to a decrease in Sn in the solution. Phosphorus provides charged adsorption sites to form a stable colloidal adsorption network, ultimately resulting in a lower tin recovery rate with higher phosphorus levels.
[0037] 2. Silicon-phosphorus synergistic interference: In the P+SiO2 system, quartz forms silicic acid after alkali dissolution and sulfuric acid acidification, which polymerizes into SiO2·nH2O colloid upon heating, and PO4... 3- Adsorbed on the silica gel surface, forming a Si-P composite colloidal interface, tin exhibits stronger adsorption capacity. Tin undergoes surface adsorption, co-precipitation, and encapsulation within the system; therefore, tin recovery decreases with increasing phosphorus concentration. In summary, silicon does not act as the primary interfering agent alone, but rather significantly enhances the adsorption and fixation of tin by forming a colloid and synergistically with phosphorus, thereby amplifying the measurement error.
[0038] 3. Interference from aluminum: Al hydrolyzes to form Al(OH)3 and forms aluminum silica gel with Si, which adsorbs and encapsulates tin. However, Al does not form a strong complex with Sn, indicating that aluminum mainly affects tin determination through hydrolysis and colloidal adsorption. Phosphorus, on the other hand, has both complexation and interfacial adsorption effects, and its inhibition of tin is more significant.
[0039] 4. Mitigating Effect of Niobium and Tantalum: While the tin recovery rate decreased with increasing concentration after adding small amounts of Nb and Ta to the P-Si-Al system, the decrease was less pronounced than in the P-Si system. Analysis suggests that Nb and Ta readily hydrolyze under acidic conditions to form colloids, and they also exhibit strong binding affinity to phosphate ions, thus consuming some phosphorus and participating in the colloidal structure construction. Furthermore, a significant competitive adsorption effect exists in the multi-component system, preventing tin from becoming the primary accumulation target and reducing its adsorption or encapsulation. Therefore, the introduction of Nb and Ta weakens the synergistic inhibitory effect of the phosphorus-silicon system on tin to some extent.
[0040] Spiking experiments were conducted on the raw ore samples with added interfering substances. The results are shown in Table 5. Table 5 Experiment with raw ore and interference factors
[0041] Actual ore sample verification results showed that different components had significantly different effects on tin recovery. Under single-factor conditions, phosphorus had the most significant inhibitory effect on tin, with a recovery rate of only 40.8% when P was 300 mg / L. In contrast, SiO2 (1500 mg / L) and Al (800 mg / L) alone achieved recoveries of 80.3% and 77.6%, respectively, indicating that they mainly affected tin determination through colloidal adsorption. In the multi-component system (P-Si-Al-Nb-Ta), the tin recovery rate was 45.8%, significantly lower than under interference-free conditions but higher than the phosphorus-only system, indicating that the introduction of Nb and Ta, through competitive binding and adsorption site dispersion, weakened the inhibitory effect of phosphorus on tin to some extent. Furthermore, the recovery rate of the raw ore sample without added exogenous elements was 67.3%, indicating that the raw ore itself already contained complex matrix effects affecting tin determination. When the sample size increased to 0.5 g, the recovery rate dropped to 8.9%, indicating that under high matrix concentration conditions, colloid formation and adsorption in the system were significantly enhanced, leading to severe tin loss. In actual mineral samples, the synergistic and competitive effects of multiple components jointly control the analytical behavior of tin, and their influence is significantly greater than that of a single-factor system.
[0042] Comparative Example 1: Determination of Tin Content by Sodium Peroxide Fusion-Single Hydrochloric Acid Acidification-ICP-OES Method Sample pretreatment: The pretreatment steps were the same as in Example 1, except that only 18 mL of hydrochloric acid was added during acidification, and hydrofluoric acid was not added; the spiked recovery experiment design was the same as in Example 1. The test method was also the same as in Example 1, and the results are shown in Table 6.
[0043] Table 6
[0044] For samples with low interference (tin concentrate, low-phosphorus aluminum niobium tantalum standard material): the results of the single hydrochloric acid system and the hydrochloric acid-hydrofluoric acid system show little difference. For samples with complex matrix (raw ore, niobium tantalum concentrate): when acidified with hydrochloric acid alone, silicon, aluminum, niobium, and tantalum easily form colloids, adsorbing and encapsulating tin, resulting in significantly lower test results and a spiked recovery rate of <90%.
[0045] In summary, after treating the sample with a sodium peroxide fusion combined with a hydrochloric acid-hydrofluoric acid system, elements such as silicon, aluminum, niobium, and tantalum exist in the form of fluorine complexes, which effectively inhibits colloid formation and the adsorption of tin, allowing tin to exist stably in the solution. This avoids the problem of low measurement values caused by colloid adsorption in traditional methods.
[0046] The specific embodiments of the present invention have been described in detail, but should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.
Claims
1. A method for determining the tin content in polymetallic ores using alkali dissolution-hydrochloric acid-hydrofluoric acid acidification complexation, characterized in that... Includes the following steps: Sample pretreatment: Place the ore sample in a container, add sodium peroxide, stir evenly, and then cover with another layer of sodium peroxide. Melt and decompose at 720~740℃. After cooling, add water at 80~90℃ to extract the melt. After further cooling, add a mixed acid of hydrochloric acid and hydrofluoric acid. Finally, make up the volume of the resulting mixed solution, shake well, and let stand. Take the supernatant and dilute it with aqua regia with a volume fraction of 5~10% to obtain the test solution; the volume fraction of hydrofluoric acid in the mixed acid is 0.3~0.6%. Determination: A standard curve was established and the characteristic spectral lines of tin in the test solution were determined using a full-spectrum direct-reading inductively coupled plasma atomic emission spectrometer. The tin content in the sample was calculated based on the standard curve.
2. The method for determining the tin content in polymetallic ores using alkali dissolution-hydrochloric acid-hydrofluoric acid acidification complexation according to claim 1, characterized in that, The elemental composition of the ore sample includes phosphorus, aluminum, silicon, niobium, and tantalum.
3. The method for determining the tin content in polymetallic ores using alkali dissolution-hydrochloric acid-hydrofluoric acid acidification complexation according to claim 1, characterized in that, The mass ratio of ore sample to total sodium peroxide is 0.1~0.5:3~5.
4. The method for determining the tin content in polymetallic ores using alkali dissolution-hydrochloric acid-hydrofluoric acid acidification complexation according to claim 1, characterized in that, The melting time is 8~12 minutes.
5. The method for determining the tin content in polymetallic ores using alkali dissolution-hydrochloric acid-hydrofluoric acid acidification complexation according to claim 1, characterized in that, The ratio of ore sample, water, and mixed acid is 0.1~0.5g: 50~70mL: 15~20mL.
6. The method for determining the tin content in polymetallic ores using alkali dissolution-hydrochloric acid-hydrofluoric acid acidification complexation according to claim 1, characterized in that, The dilution factor for the supernatant of aqua regia with a volume fraction of 5-10% is 18-22 times.
7. The method for determining the tin content in polymetallic ores using alkali dissolution-hydrochloric acid-hydrofluoric acid acidification complexation according to claim 1, characterized in that, The operating parameters of the full-spectrum direct-reading inductively coupled plasma atomic emission spectrometer are as follows: power 1.0-1.25kW, plasma gas flow rate 12.0-16.0L / min, measurement wavelength 189.925nm, auxiliary gas flow rate 1.00-2.00L / min, observation height 7-9mm, nebulizing gas flow rate 0.5-1.0L / min, reading time 5-7s, radial observation.
8. The method for determining the tin content in polymetallic ores using alkali dissolution-hydrochloric acid-hydrofluoric acid acidification complexation according to claim 1, characterized in that, The formula for calculating tin content is: in To determine the tin concentration (mg / L) in the solution, This is the final volume (mL) after dilution. To measure the volume (mL), V 0 represents the initial final volume (mL). The mass of the sample is (g).