Method for determining carbon content in non-carbonates

Abstract

The application discloses a method for determining non-carbonate carbon content, and belongs to the technical field of mineral analysis. The method comprises the following steps: performing dilute acid treatment on a sample to be measured to remove carbonate minerals, and obtaining an acid-treated sample; adding carbonate internal standard samples with different mass proportions to the acid-treated sample to prepare an automatic mineralogical analysis sample; measuring the calcium carbonate content and total carbon element content in each mixed sample through automatic mineralogical analysis; establishing a standard addition curve with the mass fraction of calcium carbonate addition as the abscissa and the mass fraction of total carbon elements as the ordinate; extrapolating the intercept of the addition amount to zero as the preliminary content of non-carbonate carbon; simultaneously calculating the carbon deviation rate and the mass change rate before and after acid treatment; and finally calculating the final content of non-carbonate carbon in the sample to be measured. The application realizes synchronous and accurate determination of the non-carbonate carbon content and the particle size distribution characteristics of carbonaceous substances, and solves the technical problems of large determination error and inability to perform synchronous characterization in the traditional method.

Description

Technical Field

[0001] This invention relates to the field of mineral analysis technology, and specifically to a method for determining the carbon content in non-carbonates. Background Technology

[0002] Accurate determination of carbon content in samples is of significant practical importance in mineral resource exploration, environmental geochemistry research, and industrial fields such as metallurgy and building materials. Carbon in natural samples typically exists in multiple forms, primarily falling into two categories: inorganic carbon (carbonate carbon) existing as carbonate minerals such as calcite and dolomite; and non-carbonate carbon existing as organic matter, elemental carbon, graphitic carbon, etc. Accurate determination of the content of non-carbonate carbon (i.e., carbon in all forms other than that bound to carbonate minerals) in carbonaceous gold ores is crucial for assessing the leaching resistance of the ore, optimizing pretreatment processes, and improving gold recovery rates.

[0003] Currently, methods for determining carbon content in carbonaceous gold ores mainly fall into two categories: chemical analysis and instrumental analysis. Combustion-infrared absorption method: This method can determine total carbon content, but it cannot distinguish between carbonate and non-carbonate carbon, and the equipment is expensive. For low-grade carbon samples, the detection accuracy is significantly affected by the sample weight and flux selection. Thermogravimetric analysis: This method indirectly estimates carbon content through weight loss characteristics at different temperature ranges, but it requires small sample volumes, and its accuracy is greatly affected by factors such as heating rate, atmospheric conditions, and interference from other volatile components. Automated process mineralogical analysis: This method can determine carbonaceous content, but it faces the following challenges: both carbonate minerals and non-carbonate carbonaceous materials in the ore show characteristic carbon peaks in energy dispersive spectroscopy (EDS), leading to carbonate carbon being mistakenly counted as non-carbonate carbon, resulting in significantly overestimated results; the epoxy resin binder in traditional sample preparation methods contains carbon, which interferes with the identification and quantification of carbonaceous materials; and there is a lack of specific calibration methods for non-carbonate carbon, resulting in large deviations in quantitative results.

[0004] In view of this, there is an urgent need to provide a method for determining the non-carbonate carbon content in carbonaceous gold ores, which can achieve specific, accurate and rapid quantification of non-carbonate carbon while effectively eliminating interference from carbonate carbon and sample preparation media. This would provide a reliable basis for the process mineralogical evaluation, pretreatment process selection and gold recovery improvement of carbonaceous refractory gold ores. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present invention provides a method for determining the carbon content in non-carbonates. By selectively removing carbonate minerals through dilute acid pretreatment, combined with palm wax sample preparation and automated mineralogical analysis, an internal standard addition method is used to establish a calcium carbonate addition-to-total carbon response curve. Preliminary values ​​of non-carbonate carbon are extrapolated, and carbon deviation rate and acid treatment yield are introduced for dual correction, ultimately achieving simultaneous and accurate determination of non-carbonate carbon content and carbonaceous particle size distribution characteristics.

[0006] This invention provides a method for determining the carbon content in non-carbonates, comprising the following steps: S1. The mineral sample to be tested is acid-treated to selectively remove carbonate minerals, resulting in an acid-treated sample. The mass change rate before and after acid treatment is then determined. S2. Add different mass fractions of carbonate internal standard to multiple acid-treated samples to obtain multiple sets of mixed internal standard samples; S3. Perform automated mineralogical analysis on the internal standard sample mixture to obtain the mass fraction of carbonate internal standard and the mass fraction of total carbon in each internal standard sample mixture. S4. Based on the mass fraction of the carbonate internal standard and the total carbon element mass fraction in step S3, construct a standard addition curve and determine the preliminary carbon content in the non-carbonate in the acid-treated sample by extrapolation; based on the theoretical carbon mass fraction of the carbonate internal standard in step S2 and the mass fraction of the carbonate internal standard measured in step S3, construct a deviation response curve and determine the carbon deviation rate. S5. Based on the carbon deviation rate and the mass change rate before and after acid treatment, the preliminary carbon content in the non-carbonate is corrected to obtain the carbon content in the non-carbonate of the mineral sample to be tested.

[0007] As a further improvement of the present invention, in step S5, the calculation formula for the carbon content in the non-carbonate mineral sample to be tested is as follows: E = b0 / K × b; Where E is the carbon content in the non-carbonate of the mineral sample to be tested; b0 is the initial carbon content in the non-carbonate; K is the carbon deviation rate; and b is the mass change rate before and after acid treatment.

[0008] As a further improvement of the present invention, in step S4, the construction of the standard addition curve includes: performing a linear regression with the mass fraction of the carbonate internal standard sample in step S3 as the abscissa and the mass fraction of total carbon element as the ordinate, and the regression equation is shown below: di2 = f × di1 + b0; Wherein, di2 is the total carbon element mass fraction; di1 is the carbonate internal standard mass fraction in step S3; f is the slope; and b0 is the intercept. Extrapolating the regression equation to zero yields the ordinate intercept, which represents the initial carbon content b0 in the non-carbonate.

[0009] As a further improvement of the present invention, in step S4, the construction of the deviation response curve includes: performing linear regression with the theoretical carbon mass fraction of the carbonate internal standard sample in step S2 as the abscissa and the carbonate internal standard sample mass fraction measured in step S3 as the ordinate to obtain the carbon deviation rate, as expressed below: di1 = K × x + q; Where K is the carbon deviation rate, which characterizes the degree of deviation of the automated mineralogical analysis system in the quantitative analysis of carbon; x is the theoretical carbon mass fraction of the carbonate internal standard; and q is the intercept. As a further improvement of the present invention, in step S2, the carbonate internal standard is one of calcium carbonate powder and magnesium carbonate powder, with a purity ≥99.95% and a particle size of 0.074mm~0.053mm; The theoretical carbon mass fraction x of the internal standard of the carbonate is calculated as follows: (mass fraction of internal standard of carbonate in step S2) × 12 / 100 or 14.25 / 100, where 12 / 100 is the mass fraction of carbon in calcium carbonate and 14.25 / 100 is the mass fraction of carbon in magnesium carbonate.

[0010] As a further improvement of the present invention, in the mixed sample of internal standard in step S2, the mass fraction of the carbonate internal standard is selected from at least four of 0.50%, 1.00%, 5.00%, 10.00%, and 25.00%.

[0011] As a further improvement of the present invention, in step S1, the acid treatment uses dilute hydrochloric acid with a volume concentration of 5% to 20% and a solid-liquid ratio of 1:(1 to 3). After the reaction is completed, the filtrate is washed until the pH of the filtrate is 6.5 to 7.5 and then dried to constant weight. The mass change rate before and after acid treatment is b = mB / mA; where mA is the sample mass before acid treatment and mB is the dried sample mass after acid treatment, which characterizes the yield of acid treatment.

[0012] As a further improvement of the present invention, in step S3, the sample surface after carbon spraying is subjected to automatic mineralogy analysis before the automatic mineralogy analysis, and the carbon layer thickness is 15nm~25nm. The internal standard mixed sample was prepared by embedding palm wax, and the mass ratio of palm wax to sample was 1:(1.5~5).

[0013] As a further improvement of the present invention, the method is applicable to the analysis and detection of carbonate-type carbonaceous gold ore, carbonaceous polymetallic ore, black shale-type ore, carbonaceous copper-molybdenum ore, and carbonaceous uranium-molybdenum ore.

[0014] As a further improvement of the present invention, before the acid treatment in step S1, the sample of mineral to be tested is further subjected to fine grinding, with the grinding fineness being less than 0.074 mm and the mass percentage being 50.0~95%.

[0015] Beneficial effects: The method provided by this invention is not limited by the type of ore and is applicable to the analysis and detection of various non-carbonate carbon ore samples, such as carbonate-type carbonaceous gold ore, carbonaceous polymetallic ore, and black shale-type ore. It provides a standardized technical solution for the process mineralogical evaluation of carbonaceous ores.

[0016] 1. Dilute acid pretreatment effectively separates carbonate carbon from non-carbonate carbon. This invention selectively decomposes and removes carbonate minerals such as calcite and dolomite from samples at room temperature through dilute hydrochloric acid treatment, allowing carbonate-bound carbon to be completely released as CO2. The acid-treated sample retains only non-carbonate carbonaceous matter, fundamentally eliminating the interference of carbonate carbon on the determination of non-carbonate carbon and solving the technical problem of existing automated mineralogical analysis techniques being unable to distinguish between the two types of carbon sources.

[0017] 2. The internal standard addition method combined with carbon deviation rate correction significantly improves quantitative accuracy. This invention uses high-purity carbonate powder as an internal standard sample added to the acid-treated sample. The response change of total carbon content at different addition levels is determined by automated mineralogical analysis to establish a standard addition curve. Simultaneously, the carbon deviation rate K is innovatively introduced to quantitatively characterize the systematic bias of the automated mineralogical analysis system for carbon. Combined with the acid treatment yield b, a dual correction is performed, ensuring that the final measurement results accurately reflect the actual content of non-carbonate carbon in the original sample.

[0018] 3. Palm wax sample preparation eliminates matrix carbon interference. This invention uses palm wax instead of traditional epoxy resin as a binder. Palm wax has an extremely low carbon content and clear energy dispersive spectroscopy characteristics. Combined with the uniform conductive layer formed by carbon spraying, it effectively eliminates the interference of the binder's carbon signal on the identification of carbonaceous materials, ensuring the accuracy of energy dispersive spectroscopy analysis.

[0019] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0020] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0021] Figure 1 This is a schematic flowchart of the method for determining the carbon content in non-carbonates provided in this embodiment of the invention. Detailed Implementation

[0022] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0024] In the description of the embodiments of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "multiple" means two or more, unless otherwise explicitly defined.

[0025] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0026] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0027] In the description of the embodiments of the present invention, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0028] To address the common problems in existing technologies for determining non-carbonate carbon in carbonaceous gold ores, such as the inability of total carbon determination to distinguish carbon speciation; insufficient selectivity, easy loss of carbonaceous matter, and lengthy procedures in chemical phase analysis; severe interference from kinetic conditions and coexisting components, resulting in poor sample representativeness in thermal analysis; and the challenges faced by automated process mineralogy analysis methods, including overlapping energy dispersive spectral signals of carbonate carbon and carbonaceous matter, interference from carbon-containing sample preparation media, and the lack of a dedicated calibration method for non-carbonate carbon, leading to poor comparability between different methods and difficulty in providing reliable data support for the evaluation of refractory leaching properties and optimization of pretreatment processes, this invention provides a method for determining the carbon content in non-carbonates. This method selectively removes carbonate minerals through dilute hydrochloric acid pretreatment, fundamentally eliminating the interference of carbonate carbon on the determination of non-carbonate carbon. High-purity carbonate powder is added as an internal standard to the acid-treated sample, and a standard addition curve is established in conjunction with automated process mineralogy analysis. A carbon deviation rate K is introduced to correct the quantitative deviation of the system. This invention enables accurate determination of non-carbonate carbon content, providing reliable data support for risk assessment of gold robbery in carbonaceous gold ores, selection of pretreatment processes, and optimization of flotation decarbonization processes, and has good prospects for industrial application.

[0029] Please refer to Figure 1 As shown, this embodiment of the invention provides a method for determining the carbon content in non-carbonates, comprising the following steps: S0, fine grinding Select 0.5~1.0 kg of the ore sample to be tested, grind it, and the grinding fineness is less than 0.074 mm with a mass ratio of 50.0~95% to obtain sample A; the preferred grinding fineness is less than 0.074 mm with a mass ratio of 70~85%.

[0030] S1. Dilute acid treatment (used to eliminate interference from existing carbonates in the sample) Take 80-150 g of the grinding sample A from step S0 and treat it with acid. The acid treatment uses dilute hydrochloric acid with a volume concentration of 5% to 20.0% and a solid-liquid ratio of 1:1 to 3 to fully decompose carbonate minerals such as calcite and dolomite in the sample, so that the carbon bound to the carbonates is completely released in the form of CO2. After the reaction is completed, the sample is soaked in water, filtered, and repeatedly washed with deionized water until the pH of the filtrate is 6.5 to 7.5 to remove residual acid and soluble salts. The sample is then dried at 105℃±2℃ to constant weight to obtain the acid-treated sample.

[0031] The yield of acid treatment (the rate of change in mass before and after acid treatment) is denoted as b, where b = mB / mA; and mA is the mass of the sample taken before acid treatment (g), and mB is the mass of the dried sample after acid treatment (g).

[0032] After treatment with dilute acid, the carbonate minerals in the sample are decomposed and removed, leaving only non-carbonate carbonaceous matter (including organic carbon, elemental carbon, graphitic carbon, etc.) in the acid-treated sample, thus achieving effective separation of carbonate carbon and non-carbonate carbon. The acid treatment involves reacting dilute hydrochloric acid at room temperature until no more foaming occurs (0.5~2.0 h), followed by soaking, washing, and filtration with water.

[0033] S2. Add internal standard sample The brightness is similar (under the condition that the contrast parameter is the same, the difference in brightness parameter is less than or equal to 10%), which facilitates subsequent automatic mineralogical testing and analysis.

[0034] Calcium carbonate (CaCO3) powder (or other carbonate powders, such as magnesium carbonate powder) was used as an internal standard, with a particle size controlled within the range of 0.074–0.053 mm, and dried to constant weight at 105℃±2℃. 3–5 g samples were taken from the acid-treated samples and mixed with different mass ratios (different mass fractions) of calcium carbonate powder (carbonate internal standard) into multiple acid-treated samples. Specifically, using the standard addition method, several portions of the same acid-treated sample were accurately weighed, and different masses of carbonate internal standard were added to each sample, so that the mass fraction of the carbonate internal standard in the mixed sample after addition was 0.50%, 1.00%, 5.00%, 10.00%, and 25.00%. At least four internal standard mixed samples were prepared, denoted as Ci, where i = 1, 2, 3, 4, and 5 correspond to the mass fraction levels of the five carbonate internal standard samples mentioned above.

[0035] The calcium carbonate is of analytical grade (≥99.95%).

[0036] S3. Sample preparation and testing analysis; An automated mineralogical analysis sample Di was prepared from sample Ci and subjected to automated mineralogical analysis. The mass fraction of carbonate internal standard and the mass fraction of total carbon were measured and denoted as di1 and di2, respectively. Among them, di1 is the mass fraction of carbonate internal standard in sample Di (%), which is obtained by automated mineralogical analysis software based on carbonate standard energy spectrum identification and statistical calculation of area ratio and binding density conversion; di2 is the mass fraction of total carbon in sample Di (%), which is quantitatively obtained by automated mineralogical analysis software based on the intensity of carbon EDS characteristic peak, including the sum of carbonate internal standard carbon and non-carbonate carbon.

[0037] The preparation of the automated mineralogical analysis sample specifically includes: using palm wax as a binder, mixing a series of samples with palm wax at a mass ratio of 1:(1.5~5), heating to melt (heating temperature is 80℃~100℃). After thorough mixing, pouring into a sample preparation mold, curing at room temperature, and then demolding; when grinding the surface to be tested, preferably using 1000 mesh or higher abrasive, grinding until the surface is smooth; when polishing, using an abrasive of 0.5 μm or lower, and controlling the polishing time to be more than 10 minutes. The carbon layer thickness of the carbon spraying treatment is controlled at 15nm~25nm to ensure good conductivity and not interfere with the energy dispersive spectroscopy identification of carbonaceous materials.

[0038] The automated mineralogical analysis uses energy dispersive spectroscopy (EDS) data from organic carbon and carbonate internal standards to identify carbon-containing minerals.

[0039] S4. Establishing curves and calculating carbon content S41. Plot a standard addition curve with the added carbonate internal standard mass fraction di1 (Ca) as the x-axis and the measured total carbon mass fraction di2 as the y-axis, and perform linear regression. The expression is as follows: di2 = f × di1 + b0; Where f is the slope and b0 is the intercept.

[0040] S42. Extrapolate the regression curve to the addition amount of zero, di1 (Ca=0), and the intercept of its ordinate is the initial carbon content b0 in the non-carbonate of the acid-treated sample.

[0041] S43. Calculation of Carbon Deviation Rate K: Using the theoretical carbon content of the carbonate internal standard corresponding to each addition level on the horizontal axis (mass fraction of carbonate internal standard in step S2 × 12 / 100 or 14.25 / 100, where 12 / 100 is the mass fraction of carbon in calcium carbonate and 14.25 / 100 is the mass fraction of carbon in magnesium carbonate) as the baseline value on the horizontal axis, and using the mass fraction di1 of the carbonate internal standard determined by automated mineralogical analysis on the vertical axis, a linear regression is performed. The regression equation expression is: di1 = K × x + q; Where K is the carbon bias rate, characterizing the degree of deviation of the automated mineralogical analysis system in the quantitative analysis of carbon; x is the theoretical carbon mass fraction of the carbonate internal standard; and q is the intercept. (K and q can be obtained by regression analysis of multiple data points using the least squares method.) The carbon deviation rate K characterizes the degree of deviation of the automated mineralogical analysis system in the quantitative analysis of carbon, and is used for subsequent data correction.

[0042] S5. Correction calculation of final carbon content The carbon content (E) in the non-carbonate fraction of the sample to be tested is calculated as follows: E = b0 / K × b; Where b0 is the initial carbon content (%) in the non-carbonate of the acid-treated sample; K is the carbon deviation rate (dimensionless); and b is the acid treatment yield, i.e., the mass change rate (%) before and after acid treatment.

[0043] The correction process takes into account both the carbon quantification bias of the automated mineralogy analysis system itself (K correction) and the sample mass loss during acid treatment (weight loss correction during acid treatment), ensuring that the final result accurately reflects the true content of non-carbonate carbon in the original sample.

[0044] Example 1 Example 1 of this invention provides a method for determining the carbon content in non-carbonate ore. In specific application, the ore sample to be tested is a carbonate-type carbonaceous gold ore with an estimated total carbon content of approximately 3.00% or more, of which approximately 2.20% is carbonate carbon and approximately 1.00% is non-carbonate carbon. Since the direct leaching recovery rate of gold is less than 10%, it is necessary to determine the carbon content in non-carbonate ore. The method includes the following steps: S0, fine grinding A 1.0 kg sample was selected and ground using a conical ball mill. The grinding fineness was less than 0.074 mm, and the mass percentage was 75%, to obtain sample A. The sample A was then mixed and reduced for later use.

[0045] S1. Dilute acid treatment (to eliminate interference from existing carbonates in the sample) Take 100.00 g of grinding sample A from step S0 and treat it with acid; Dilute hydrochloric acid with a volume concentration of 10.0% and a solid-liquid ratio of 1:2 (200 ml dilute hydrochloric acid solution) was used, and the reaction was carried out at room temperature for 1 h. After the reaction was completed, the sample was soaked in water, filtered, and repeatedly washed with deionized water until the pH of the filtrate was 7.0 to remove residual acid and soluble salts. The sample was dried at 105℃±2℃ to constant weight to obtain the acid-treated sample, and the weight was mB=82.52 g.

[0046] The yield of acid treatment (the rate of change in mass before and after acid treatment) is b = mB / mA = 82.50%.

[0047] S2. Add internal standard sample Calcium carbonate (CaCO3) powder (purity 99.99%, particle size 0.060 mm) was used as an internal standard and dried at 105℃±2℃ to constant weight. Take less than 4.0 g of sample from the acid-treated sample and mix calcium carbonate powder in different mass ratios into multiple acid-treated samples. The mass of the mixed samples is 4.0 g. See Table 1 for sample mixing details.

[0048] Samples C1 to C4 were obtained with calcium carbonate mass fractions of 0.50%, 1.00%, 5.00%, and 10.00%.

[0049] Table 1 Sample Preparation Details S3. Sample preparation and testing analysis; An automated mineralogical analysis sample Di was prepared from sample Ci, and automated mineralogical analysis was performed to determine the contents (mass fraction) of calcium carbonate internal standard and the contents (mass fraction) of total carbon, which were di1 and di2, respectively. The series of optical sections were tested in an automated mineralogy analysis system with an accelerating voltage of 20 kV, a working distance of 12 mm, and a scanning area of ​​20 mm². Standard energy dispersive spectroscopy libraries for calcium carbonate, organic carbon, and palm wax were established. The content (mass fraction) of calcium carbonate internal standard (di1) and the content (mass fraction) of total carbon (di2) in each sample were measured. The results are detailed in Table 2.

[0050] Using palm wax as a binder, a series of samples were mixed with palm wax at a mass ratio of 1:2 and heated to melt (heating temperature: 90℃). After thorough mixing, the mixture was poured into a sample preparation mold and allowed to cure at room temperature before demolding. Grinding was performed sequentially using 200-grit, 500-grit, and 1000-grit sandpaper, followed by polishing with 3μm, 1μm, and 0.5μm diamond polishing pastes, for a total grinding and polishing time of 40 minutes. Carbon spraying was then applied (carbon layer thickness 15 nm).

[0051] Table 2 Test Analysis Results S4. Establishing curves and calculating carbon content S41. Plot a standard addition curve with the mass fraction of calcium carbonate internal standard di1 (Ca) determined in step S3 as the abscissa and the measured mass fraction of total carbon element di2 as the ordinate. The expression is as follows: di2 =0.1214× di1 + 1.2895, R 2 =0.9999.

[0052] S42. Extrapolate the regression curve to the addition amount of zero, di1 (Ca=0), and the intercept of its ordinate is the preliminary carbon content in the non-carbonate of the acid-treated sample, b0=1.2895.

[0053] S43, carbon deviation rate K, using the least squares method, the regression results for the four data points are: k = 0.98, q = 0.04, R² = 0.9999.

[0054] S5. Correction calculation of final carbon content The carbon content (E) in the non-carbonate fraction of the ore sample to be tested is calculated as follows: E=b0 / K×b=1.2895 / 0.98×82.50%=1.0852%.

[0055] Verification: Select a gold ore sample with a matrix similar to the ore sample to be tested (excluding carbon in non-carbonates). Add a known amount of high-purity graphite carbon powder (purity ≥99.99%, particle size -325 mesh) to the ore sample to be tested to prepare a simulated standard sample (the carbon content value can be calculated). Use this method to test it. Compare the amount added with the result E of the present invention. The relative deviation is ≤3%, which proves that the result of the method of the present invention is reliable.

[0056] In summary, this invention discloses a method for determining the carbon content in non-carbonates, belonging to the field of mineral analysis technology. The method includes: finely grinding the sample to be tested and then treating it with dilute acid to remove carbonate minerals, obtaining an acid-treated sample; adding a series of proportions of internal carbonate standards to the acid-treated sample, and preparing an automated mineralogical analysis sample using palm wax as a binder; determining the calcium carbonate content and total carbon content in each mixed sample using automated mineralogical analysis, establishing a standard addition curve with the calcium carbonate addition amount as the abscissa and the total carbon content as the ordinate, and extrapolating to the intercept where the addition amount is zero as the preliminary value of non-carbonate carbon; simultaneously calculating the carbon deviation rate (correcting the carbon quantitative deviation of the automated mineralogical analysis system) and the acid treatment yield (the rate of mass change before and after acid treatment, used to correct for mass loss); and finally calculating the final non-carbonate carbon content in the original sample. This invention achieves simultaneous and accurate determination of non-carbonate carbon content and carbonaceous particle size distribution characteristics, solving the technical problems of large measurement errors and inability to simultaneously characterize traditional methods.

[0057] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for determining the carbon content in non-carbonates, characterized in that, Includes the following steps: S1. The mineral sample to be tested is acid-treated to selectively remove carbonate minerals, resulting in an acid-treated sample. The mass change rate before and after acid treatment is then determined. S2. Add different mass fractions of carbonate internal standard to multiple acid-treated samples to obtain multiple sets of mixed internal standard samples; S3. Perform automated mineralogical analysis on the internal standard sample mixture to obtain the mass fraction of carbonate internal standard and the mass fraction of total carbon in each internal standard sample mixture. S4. Based on the mass fraction of the carbonate internal standard and the total carbon element mass fraction in step S3, construct a standard addition curve and determine the preliminary carbon content in the non-carbonate in the acid-treated sample by extrapolation; based on the theoretical carbon mass fraction of the carbonate internal standard in step S2 and the mass fraction of the carbonate internal standard measured in step S3, construct a deviation response curve and determine the carbon deviation rate. S5. Based on the carbon deviation rate and the mass change rate before and after acid treatment, the preliminary carbon content in the non-carbonate is corrected to obtain the carbon content in the non-carbonate of the mineral sample to be tested.

2. The method for determining the carbon content in non-carbonates according to claim 1, characterized in that, In step S5, the carbon content in the non-carbonate mineral sample to be tested is calculated using the following formula: E = b0 / K × b; Where E is the carbon content in the non-carbonate of the mineral sample to be tested; b0 is the initial carbon content in the non-carbonate; K is the carbon deviation rate; and b is the mass change rate before and after acid treatment.

3. The method for determining the carbon content in non-carbonates according to claim 2, characterized in that, In step S4, the construction of the standard addition curve includes: performing a linear regression with the mass fraction of the carbonate internal standard sample from step S3 as the abscissa and the mass fraction of total carbon as the ordinate. The regression equation is shown below: di2 = f × di1 + b0; Wherein, di2 is the total carbon element mass fraction; di1 is the carbonate internal standard mass fraction in step S3; f is the slope; and b0 is the intercept. Extrapolating the regression equation to zero yields the ordinate intercept, which represents the initial carbon content b0 in the non-carbonate.

4. The method for determining the carbon content in non-carbonates according to claim 3, characterized in that, In step S4, the construction of the deviation response curve includes: performing linear regression with the theoretical carbon mass fraction of the carbonate internal standard sample in step S2 as the abscissa and the mass fraction of the carbonate internal standard sample measured in step S3 as the ordinate to obtain the carbon deviation rate, as expressed below: di1 = K × x + q; Where K is the carbon deviation rate, which characterizes the degree of deviation of the automated mineralogical analysis system in the quantitative analysis of carbon; x is the theoretical carbon mass fraction of the carbonate internal standard; and q is the intercept.

5. The method for determining the carbon content in non-carbonates according to claim 4, characterized in that, In step S2, the internal standard of carbonate is one of calcium carbonate powder and magnesium carbonate powder, with a purity ≥99.95% and a particle size of 0.074mm~0.053mm; The theoretical carbon mass fraction x of the internal standard of the carbonate is calculated as follows: (mass fraction of internal standard of carbonate in step S2) × 12 / 100 or 14.25 / 100, where 12 / 100 is the mass fraction of carbon in calcium carbonate and 14.25 / 100 is the mass fraction of carbon in magnesium carbonate.

6. The method for determining the carbon content in non-carbonates according to claim 1, characterized in that, In step S2, the mass fraction of the carbonate internal standard in the mixed sample is selected from at least four of the following: 0.50%, 1.00%, 5.00%, 10.00%, and 25.00%.

7. The method for determining the carbon content in non-carbonates according to claim 1, characterized in that, In step S1, the acid treatment uses dilute hydrochloric acid with a volume concentration of 5% to 20% and a solid-liquid ratio of 1:(1 to 3). After the reaction is completed, the filtrate is washed until the pH is 6.5 to 7.5 and then dried to constant weight. The mass change rate before and after acid treatment is b = mB / mA; where mA is the sample mass before acid treatment and mB is the dried sample mass after acid treatment, which characterizes the yield of acid treatment.

8. The method for determining the carbon content in non-carbonates according to claim 1, characterized in that, In step S3, the sample surface after carbon spraying is subjected to automatic mineralogy analysis, and the carbon layer thickness is 15nm~25nm. The internal standard mixed sample was prepared by embedding palm wax, and the mass ratio of palm wax to sample was 1:(1.5~5).

9. The method for determining the carbon content in non-carbonates according to claim 1, characterized in that, The method is applicable to the analysis and detection of carbonate-type carbonaceous gold ore, carbonaceous polymetallic ore, black shale-type ore, carbonaceous copper-molybdenum ore, and carbonaceous uranium-molybdenum ore.

10. The method for determining the carbon content in non-carbonates according to claim 1, characterized in that, Before the acid treatment in step S1, the sample to be tested is further subjected to fine grinding, with a grinding fineness of less than 0.074 mm and a mass ratio of 50.0-95%.

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