Process method for detecting gold and silver grades in gold ore

Abstract

The invention relates to the technical field of analytical chemistry and geological testing, and discloses a process method for detecting the grade of gold and silver in gold ore, which comprises the following steps: adding a polybasic mixed acid system containing solid ammonium chloride into the ore; two-stage gradient heating is executed, in the high-temperature stage, solid ammonium chloride is used for maintaining supersaturation of liquid-phase chloride ions, an acid molten salt coupling medium environment is constructed, and a silver ion complexing state is locked through a thermodynamic chloride anchor mechanism; phosphate radicals and tartaric acid are introduced to carry out in-situ chemical masking and steric hindrance stabilizing treatment on iron ions and antimony and tin elements respectively; according to the method, through a non-volatile chlorine reservoir compensation mechanism and a multi-dimensional matrix masking strategy, the problems of silver precipitation and complex matrix spectrum interference caused by chlorine source volatilization in high-temperature open digestion are solved, and the accuracy of gold and silver detection is ensured.

Description

Technical Field

[0001] This invention relates to a process for detecting gold and silver grades in gold ore, belonging to the field of analytical chemistry and geological testing technology. Background Technology

[0002] Currently, in precious metal mineral exploration and metallurgical process control, the wet digestion method using aqua regia combined with inductively coupled plasma atomic emission spectrometry (ICP-AES) or mass spectrometry to determine the gold and silver grades in ores has become the mainstream technology for commercial laboratories to process batches of geological samples due to its multi-element simultaneous analysis capability and high-throughput processing advantages. The basic chemical principle of this technical route lies in using the strong oxidizing property of nitric acid to oxidize gold into an ionic state, and using chloride ions provided by hydrochloric acid to form a complex with silver to maintain its stability in the liquid phase. To avoid the problems of acid mist and chlorine volatilization that are easily generated at high temperatures in traditional strong acid systems, the industry has begun to try to change the chemical composition of the digestion system. For example, publicly available... Chinese invention patent application CN119779806A discloses a method for determining silver in gold ore. It uses a bromine water and sodium chloride system instead of traditional strong acids, utilizing the strong oxidizing properties of bromine and the coordination properties of chlorine to achieve silver leaching and determination. Although the non-strong acid oxidation system improves the working environment, it is difficult to release deeply encapsulated fine gold and silver particles when dealing with complex geological formations and difficult-to-process gold ores with tightly encapsulated silica gangue. This is because it lacks the ability of hydrofluoric acid to break down the silicate mineral lattice and lacks the support of a high-temperature strong acid environment to provide intense oxidation kinetics, resulting in lower detection results. Furthermore, it does not fully consider the background interference of high-iron and high-antimony matrix spectral measurements, making it difficult to meet the requirements of high-precision analysis.

[0003] However, when processing gold ores with complex silicate gangue components, in order to break the mineral lattice and release the finely encapsulated gold and silver particles, the process usually requires the introduction of hydrofluoric acid and the increase of the digestion temperature to 180°C to 200°C. This engineering operation requirement is objectively constrained by the thermodynamic properties of hydrochloric acid in an open system. Since the boiling point of the azeotropic system formed by hydrochloric acid and water is approximately 108.6°C, when the system temperature exceeds this azeotropic point, the hydrogen chloride gas, which is the main source of the coordinating agent, undergoes violent physical volatilization, leading to an exponential decrease in the chloride ion activity in the liquid phase in the later stage of the reaction. According to the principle of coordination chemical equilibrium, the decrease in chloride ion concentration will directly lead to a decrease in the stability of silver chloride complex ions, thereby triggering the transformation of silver ions into the insoluble silver chloride solid phase, causing a systematic negative bias in the detection results; specifically, the existing technology in The following technical limitations exist when processing such complex matrix mineral samples: 1. There is an irreconcilable contradiction between high-temperature digestion efficiency and the stability of silver ions in the liquid phase. Simply increasing the temperature can promote lattice breakage but exacerbates the volatilization of chlorine source and the precipitation of silver. Adding acid in the later stage faces the retardation effect of precipitation aging and difficulty in redissolution; 2. The high iron content commonly associated with gold ore forms high-concentration iron ions after digestion. The rich emission lines generated by these ions in the plasma light source will cause spectral overlap interference with the characteristic spectra of trace gold and silver, reducing the signal-to-noise ratio of low-content samples; 3. In the volume fixation stage after digestion, as the system temperature decreases and the acidity changes, elements such as antimony and tin associated with the ore are prone to hydrolysis to generate colloidal particles. These particles capture gold and silver ions in the solution through physical adsorption, introducing hidden analytical errors.

[0004] Therefore, the technical problem to be solved by this invention is how to construct a process that can maintain high chloride ion activity in a high-temperature open system to lock the silver ion phase and simultaneously eliminate the spectral interference of the high-iron matrix and the effects of hydrolysis and adsorption of associated elements. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A process for detecting gold and silver grade in gold ore, comprising the following steps: Step 101: Add the gold ore to be tested and the digestion reagent consisting of nitric acid, hydrochloric acid, hydrofluoric acid and solid ammonium chloride to the digestion container to establish the initial detection reaction system; Step 102: Execute a two-stage gradient heating program: In the first stage from 100℃ to 120℃, the free radicals released by the reverse aqua regia system are used to oxidize the sulfides and organic carbon in the gold ore to be tested; In the second stage from 180℃ to 200℃, the supersaturated state of solid ammonium chloride in the liquid phase is maintained to construct a coupling medium environment between acidic molten salt and high-boiling-point acid, and the silver ions released from the gold ore to be tested are locked into a tetrachlorosilver complex state by using the thermodynamic chlorine anchoring mechanism, thus blocking the nucleation path of silver chloride crystal nuclei; Step 103: In the initial detection reaction system, an inorganic oxyacid containing phosphate and tartaric acid as an organic multidentate ligand are introduced. The affinity of phosphate with the ferric ions in the initial detection reaction system is used to generate an inner-orbital complex in situ, which suppresses the background interference of iron spectral lines. Tartaric acid is used to chelate with antimony and tin elements in the gold ore to be tested, which produces a steric stabilizing effect to isolate antimony and tin elements and suppress their hydrolysis reaction during the volume dilution stage. Step 104: After adjusting the volume of the processed liquid phase, collect the atomic emission spectrum signal and calculate the gold and silver grades based on the characteristic peak intensity of the atomic emission spectrum signal.

[0006] Preferably, in step 102, the chloride ion concentration C in the coupling medium environment is maintained. Cl - Satisfies the following relationship: C Cl -≥2.5mol / L; where C Cl - This is the initial detection reaction system after the chloride ion molar concentration is dynamically adjusted as the liquid phase shrinks during the second stage; the coupling medium environment uses the high-temperature solubility characteristics of solid ammonium chloride to offset the concentration decrease caused by the volatilization of the chloride source, and is used to maintain the chloride ion chemical potential under the condition of liquid phase volume reduction.

[0007] Preferably, in step 101, the ratio of the added mass of solid ammonium chloride to the sampled mass of the gold ore to be tested is 2:1 to 3:1.

[0008] Preferably, in step 102, the temperature holding time in the second stage is 30 min to 60 min.

[0009] Preferably, in step 103, the inorganic oxyacid is phosphoric acid, and the volume fraction of phosphoric acid in the liquid phase after volume adjustment is 2% to 5%.

[0010] Preferably, in step 104, an inductively coupled plasma atomic emission spectrometer is used to acquire atomic emission spectral signals, and the wavelengths for measuring gold and silver are 242.795 nm for gold and 328.068 nm for silver.

[0011] Preferably, in step 103, tartaric acid blocks the path of adsorbing silver tetrachlorotrioxide complex by encapsulating the antimony and tin metal cations, thus maintaining the physical homogeneity of the initial detection reaction system after volume dilution.

[0012] Preferably, in step 101, the sample size of the gold ore to be tested is 10g to 25g.

[0013] Preferably, in step 101, the volume ratio of nitric acid, hydrochloric acid, and hydrofluoric acid is 1:3:1.

[0014] Preferably, before performing step 104, the initial detection reaction system needs to be allowed to stand at a controlled ambient temperature for no less than 24 hours to verify the effectiveness of the thermodynamic chlorine anchoring mechanism and steric stabilization effect in maintaining the homogeneity of the liquid phase.

[0015] Compared to existing technologies, the advantages of this invention are as follows: In the process of detecting gold and silver grades, by introducing a non-volatile solid chloride into the strong acid digestion system, the physical paradox between the digestion temperature requirement and the volatilization characteristics of the chlorine source in traditional wet analysis is resolved. In the process of relying on high temperature to destroy the silicate mineral lattice, this solid chloride acts as a non-volatile chlorine reservoir. When the liquid phase volume shrinks due to the azeotropic volatilization of hydrochloric acid, its colligative properties force the chloride ions in the residual liquid phase to remain in a supersaturated state, compensating for the ligand depletion caused by thermal acid escape. This allows the system to maintain a suitable coordination environment for the stable existence of silver ions for a long time under normal pressure. At the same time, the increased liquid phase boiling point due to the high concentration of salt effect enables deep cell disruption of insoluble inclusions. This process ensures that gold and silver elements can exist in a single phase under harsh thermodynamic conditions. The stable coexistence of ions eliminates the risk of precipitation caused by chlorine depletion, ensuring the authenticity of ore grade detection. Furthermore, by introducing specific inorganic oxyacid components during the digestion stage, a signal purification pathway for high-iron matrix ores is constructed. The phosphate functional group in the system utilizes its strong affinity for ferric ions to generate a colorless and stable inner-orbital complex in situ in the liquid phase. This chemical structure physically locks the outer electrons of ferric ions, reducing their radiative transition probability in the plasma excitation source. This suppresses the coverage and interference of dense emission lines of iron elements on the characteristic wavelengths of trace gold and silver at the source of signal generation. This spectral optimization strategy based on chemical morphology regulation improves the signal-to-noise ratio and resolution of target element detection signals in complex matrix backgrounds without increasing physical separation steps. Attached Figure Description

[0016] Figure 1 This is a flowchart of the steps in the method for detecting the gold and silver grade of gold ore according to the present invention; Figure 2 This is a logical architecture diagram of the detection process technology principle and key elements of the present invention.

[0017] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0019] A process for detecting gold and silver grade in gold ore, comprising the following steps: Step 101: Add the gold ore to be tested and the digestion reagent consisting of nitric acid, hydrochloric acid, hydrofluoric acid and solid ammonium chloride to the digestion container to establish the initial detection reaction system; Step 102: Execute a two-stage gradient heating program: In the first stage from 100℃ to 120℃, the free radicals released by the reverse aqua regia system are used to oxidize the sulfides and organic carbon in the gold ore to be tested; In the second stage from 180℃ to 200℃, the supersaturated state of solid ammonium chloride in the liquid phase is maintained to construct a coupling medium environment between acidic molten salt and high-boiling-point acid, and the silver ions released from the gold ore to be tested are locked into a tetrachlorosilver complex state by using the thermodynamic chlorine anchoring mechanism, thus blocking the nucleation path of silver chloride crystal nuclei; Step 103: In the initial detection reaction system, an inorganic oxyacid containing phosphate and tartaric acid as an organic multidentate ligand are introduced. The affinity of phosphate with the ferric ions in the initial detection reaction system is used to generate an inner-orbital complex in situ, which suppresses the background interference of iron spectral lines. Tartaric acid is used to chelate with antimony and tin elements in the gold ore to be tested, which produces a steric stabilizing effect to isolate antimony and tin elements and suppress their hydrolysis reaction during the volume dilution stage. Step 104: After adjusting the volume of the processed liquid phase, collect the atomic emission spectrum signal and calculate the gold and silver grades based on the characteristic peak intensity of the atomic emission spectrum signal.

[0020] Preferably, in step 102, the chloride ion concentration C in the coupling medium environment is maintained. Cl - Satisfies the following relationship: C Cl -≥2.5mol / L; where C Cl - This is the initial detection reaction system after the chloride ion molar concentration is dynamically adjusted as the liquid phase shrinks during the second stage; the coupling medium environment uses the high-temperature solubility characteristics of solid ammonium chloride to offset the concentration decrease caused by the volatilization of the chloride source, and is used to maintain the chloride ion chemical potential under the condition of liquid phase volume reduction.

[0021] Preferably, in step 101, the ratio of the added mass of solid ammonium chloride to the sampled mass of the gold ore to be tested is 2:1 to 3:1.

[0022] Preferably, in step 102, the temperature holding time in the second stage is 30 min to 60 min.

[0023] Preferably, in step 103, the inorganic oxyacid is phosphoric acid, and the volume fraction of phosphoric acid in the liquid phase after volume adjustment is 2% to 5%.

[0024] Preferably, in step 104, an inductively coupled plasma atomic emission spectrometer is used to acquire atomic emission spectral signals, and the wavelengths for measuring gold and silver are 242.795 nm for gold and 328.068 nm for silver.

[0025] Preferably, in step 103, tartaric acid blocks the path of adsorbing silver tetrachlorotrioxide complex by encapsulating the antimony and tin metal cations, thus maintaining the physical homogeneity of the initial detection reaction system after volume dilution.

[0026] Preferably, in step 101, the sample size of the gold ore to be tested is 10g to 25g.

[0027] Preferably, in step 101, the volume ratio of nitric acid, hydrochloric acid, and hydrofluoric acid is 1:3:1.

[0028] Preferably, before performing step 104, the initial detection reaction system needs to be allowed to stand at a controlled ambient temperature for no less than 24 hours to verify the effectiveness of the thermodynamic chlorine anchoring mechanism and steric stabilization effect in maintaining the homogeneity of the liquid phase.

[0029] Example 1: In this example, a gold-bearing iron ore-quartz vein type ore was selected as the gold ore to be tested. It has a sulfur content of more than 25%, an iron content of more than 20%, and an antimony content of about 0.5%. The fine gold and silver particles are encapsulated by a silicate lattice. Weigh 10g to 25g of the gold ore to be tested, ground to 200 mesh, and place it in a digestion container. Establish an initial detection reaction system consisting of nitric acid, hydrochloric acid, hydrofluoric acid, and solid ammonium chloride in a volume ratio of 1:3:1. The mass of solid ammonium chloride added is 2 to 3 times the mass of the gold ore sample. A two-stage gradient heating program is applied to the initial detection reaction system. In the first stage (100℃ to 120℃), sulfides and organic carbon are oxidized using a reverse aqua regia system. In the second stage (180℃ to 200℃), the silicate lattice is destroyed using hydrofluoric acid, and a second-stage high-temperature digestion process is performed. The physical criteria for the heating endpoint are set as dual constraints of liquid phase rheological characteristics and volume reduction rate. The liquid phase state in the digestion container is continuously monitored. When the foam on the bottom of the container changes from rapidly bursting large bubbles to fine microbubbles with a residence time exceeding 2 seconds, and the remaining liquid volume reaches 15% to 20% of the initial total acid content, the heat source is removed and air cooling is performed. To eliminate subjective judgment errors, a process is introduced... The liquid surface monitoring logic is based on a 10Hz sampling frequency: When the total weight loss of the digestion container, as measured by the electronic balance, reaches 80.0% to 85.0% of the initial acid volume weight, a visual sensor is simultaneously used to confirm that the coverage of fine microbubbles with a diameter less than 2mm on the liquid surface exceeds 90%, and the average residence time of the microbubbles from generation to rupture is greater than 3.5s. At this point, the kinematic viscosity of the liquid phase, indirectly calculated by the sensor, has reached the range of 1.2cSt to 1.5cSt, exhibiting laminar flow characteristics similar to glycerol. This indicates that the acidic molten salt coupling medium has been successfully constructed. The operating procedure defines the critical state at which the acidic molten salt coupling medium is successfully constructed. The high concentration of chloride ions in the system and the residual high-boiling-point acid form a quasi-molten fluid with the best silver ion capture ability, limiting the engineering risks of excessive evaporation leading to volatilization loss of gold chloride or salt caking that cannot be re-dissolved. Under these conditions of high temperature and liquid phase volume reduction to one-fifth of the initial volume, solid ammonium chloride acts as a non-volatile chloride reservoir, maintaining the chloride ion molar concentration C in the liquid phase. Cl - Satisfies C Cl With a concentration ≥2.5 mol / L, this high concentration of chloride ions constructs a coupling medium environment between the acidic molten salt and the high-boiling-point acid. Through a thermodynamic chloride anchoring mechanism, the released silver ions are locked in a tetrachlorosilver complex state, i.e., [AgCl4]. 3- This inhibits the formation of silver chloride crystal nuclei.

[0030] Before adjusting the volume, 5% to 10% by volume of concentrated phosphoric acid as an inorganic oxyacid and 1% to 3% by mass of tartaric acid are introduced into the system. The phosphate ions in the concentrated phosphoric acid react with ferric ions to form a colorless inner-orbital complex, namely [Fe(PO4)2]. 3-To suppress interference from ferrospectral lines, tartaric acid undergoes a chelation reaction with antimony and tin, generating a steric stabilizing effect that inhibits the formation of hydrolyzed colloids and the adsorption of silver tetrachlorosulfonate complexes. After volume adjustment, the test solution is placed in a constant-temperature settling zone with temperature fluctuations controlled within ±2℃ and kept static for at least 24 hours. During the settling process, tartaric acid forms chelates with antimony and tin, completing the configuration transformation and reaching thermodynamic equilibrium. Potentially metastable silica gel particles are removed by gravity sedimentation. Before instrumental testing, laser scattering or visual inspection confirms that there is no Tyndall effect at 2 cm below the liquid surface, and only the turbidity index of the solution meets the tolerance requirements of the spectral sample introduction system. The atomic emission spectroscopy signal acquisition program was initiated to avoid scattering interference caused by the plasma excitation process of tiny suspended particles. After volume adjustment using a medium containing 10% to 15% hydrochloric acid, yttrium and scandium were added as internal standard elements. The analytical solution to be tested was introduced into the inductively coupled plasma atomic emission spectrometer. Yttrium was used to correct for spectral intensity fluctuations, and scandium was used to correct for atomization efficiency drift. Atomic emission spectral signals of gold and silver were acquired at wavelengths of 242.795 nm and 328.068 nm, respectively, and the grades were calculated. The test results showed that the gold and silver recovery rates remained within the range of 98.5% to 101.5%.

[0031] Example 2: This example uses refractory gold concentrate powder from a beneficiation plant in the Jiaodong gold mining area of ​​Shandong Province as the test object. The mineralogical characteristics of this powder are: sulfur content 28.5%, iron content 24.2%, and antimony content 0.65%. Gold and silver minerals are present as micron-sized inclusions within the pyrite and arsenopyrite lattices. The experimental platform uses a graphite digestion instrument with precise temperature control, achieving a temperature accuracy of ±0.5℃ and an inter-pore temperature difference of less than 1.0℃. The spectral detection terminal uses an inductively coupled plasma atomic emission spectrometer (ICP-AES), with an optical resolution better than 0.007nm at 200nm. To simulate signal disturbances in an industrial testing environment, the ICP-AES is used... A power fluctuation noise of 1.5% was introduced into the plasma radio frequency generator. The experimental design included the sample group of this invention and control sample groups in three dimensions to verify the synergistic mechanism of the core technical features and the physical constraints of the parameter boundaries. The parameter settings of the sample group of this invention followed the preferred window defined by this invention. 20g of gold ore to be tested was weighed, and 60g of solid ammonium chloride was added. The digestion temperature was set to 190℃. The control sample groups included: a partially missing control group A, which did not add solid ammonium chloride and only used liquid acid; an out-of-range control group B, which set the second-stage digestion temperature to 220℃; and an out-of-range control group C, which reduced the amount of solid ammonium chloride added to 0.5 times the sample mass of the gold ore to be tested.

[0032] The setting of the solid ammonium chloride addition ratio is based on a trade-off between chloride ion saturation and the physical properties of the system. The main factors affecting this parameter are the liquid phase volume shrinkage rate at high temperatures and the solubility limit of ammonium chloride in acidic media. If the addition amount is too low, as the liquid phase evaporates, the total amount of chloride ions in the residual liquid phase will be insufficient to maintain C. Cl - The complexation threshold is ≥2.5 mol / L; if the addition amount is too high, the supersaturated precipitated salt crystals will encapsulate unreacted mineral particles and hinder mass transfer. Gradient preliminary experimental data show that under typical conditions where the liquid phase volume is reduced to 20%, a mass ratio of 2 to 3 times is the effective range for maintaining the liquid phase chloride ion concentration at 3.0 mol / L to 4.5 mol / L without large-scale salting out. After the experiment started, each group of samples underwent a synchronous physicochemical evolution process. In the first stage, during the isothermal oxidation period at 110℃, a large amount of yellow-brown nitrogen oxide fumes were observed to escape from all sample groups, indicating that the sulfide matrix was decomposed. After entering the second stage and heating to 190℃, the digestion solution of some missing control group A changed from clear to turbid, and a white curd-like precipitate appeared at the bottom of the cup. X-ray diffraction Characterization revealed that the main phase of the precipitate was silver chloride. This phenomenon corresponds to the physical azeotropic volatilization of hydrochloric acid in the liquid phase in the absence of solid ammonium chloride as a non-volatile chloride reservoir, causing the chloride ion concentration to drop below the solubility product critical point, inducing the precipitation of silver ions. In the out-of-range control group B, after reaching 220℃, the liquid phase volume rapidly shrank to a dry state within 15 minutes. The precipitation of solute resulted in a resolution rate of less than 85% during the subsequent volume adjustment process, and some gold elements were lost in the form of volatile gold chloride dimers due to local overheating. In the out-of-range control group C, fine suspended particles appeared in the digestion solution in the later stage of the reaction. Data monitoring showed that its liquid phase chloride ion concentration dropped to 1.2 mol / L at the reaction endpoint, failing to form [AgCl4] sufficient to stabilize a high concentration of silver ions. 3- The dominant region causes some silver to exist in the form of silver chloride colloid.

[0033] The sample of this invention remained homogeneous and clear throughout the high-temperature stage. No solid phase precipitation was observed when the liquid phase volume decreased to 15% of its initial volume. After the introduction of concentrated phosphoric acid and tartaric acid during the volume adjustment stage, the originally deep yellow ferric solution instantly transformed into a light-colored transparent solution, indicating that the phosphate ions dissolved the chromophore Fe. 3+ It transforms into a colorless inner-orbital complex [Fe(PO4)2]. 3-Quantitative analysis of the spectral detection data showed that, under a noise environment with 1.5% RF power fluctuation, the gold and silver recovery rates of each group exhibited gradient differences. The silver recovery rate of the partially missing control group A was 62.4%, while the gold recovery rate of the out-of-range control group B was 88.7% and the silver recovery rate was 91.2%, with a relative standard deviation of up to 5.8% between parallel samples. The silver recovery rate of the out-of-range control group C was 93.5%, and the detection values ​​showed a decreasing trend after long-term static storage. The gold recovery rate of the sample group of this invention remained stable at 99.82%, and the silver recovery rate remained stable at 100.15%, with relative standard deviations of less than 1.2% for parallel samples. In the original data without internal standard correction, the signal intensity fluctuation reached 2.83% due to the influence of simulated noise; after correction with scandium and yttrium dual internal standards... The processed data had its signal fluctuation amplitude compressed to within 0.27%. Comparative analysis of the spectral background signal-to-noise ratio showed that in the blank control spectrum without the addition of phosphoric acid and tartaric acid, the background of the iron spectral line near the gold analysis line at 242.795 nm was raised, resulting in a signal-to-noise ratio of less than 10 for low-content gold. In the spectrum of the sample group of this invention, thanks to the chemical masking of iron and antimony ions, the background radiation intensity was reduced by 85.4%, and the signal-to-noise ratio of the gold analysis line was improved to 65.2, ensuring the detection capability for low-grade gold ore of 0.1 g / t. The experimental data confirmed that the acidic molten salt environment constructed by solid ammonium chloride is a necessary physical condition for solving the problem of silver ion precipitation, and the temperature window of 180°C to 200°C and the addition amount of 2 to 3 times are the engineering optimal solution after balancing thermodynamic stability and kinetic mass transfer efficiency.

[0034] Example 3: This example addresses the industrial application scenario where the sulfide content in the gold ore to be tested fluctuates drastically and the detection accuracy requirements are extremely high. It provides a standardized engineering procedure based on a chemometric model to adaptively determine the amount of solid ammonium chloride added and accurately determine the endpoint of the molten salt phase. When processing complex ore samples with batch-to-batch sulfur content differences exceeding 15%, if solid ammonium chloride is added only according to a fixed multiple, the detection results are easily skewed due to differences in chlorine source consumption kinetics. Therefore, this detection process introduces an effective chlorine surplus control logic. The calibration process of the various coefficients involved in this logic is as follows: The sulfur consumption coefficient is set to 0.1. The calibration method is to conduct gradient experiments on 20 groups of samples with different sulfur contents at 110℃. By measuring the partial pressure of hydrogen chloride in the reaction gas in real time, it is determined that each 1% mass fraction of sulfur element requires an additional 0.1g of effective chlorine to be consumed during the oxidation process; iron complexation... The compensation coefficient was set to 0.04. The molar ratio of iron ions to chloride ions was determined by gradually adding chloride ions dropwise to 10g of pure iron matrix in an acidic molten salt solution at 190℃ until the solution changed from yellow turbidity to complete clarity. The basic molten salt construction constant was fixed at 1.5, its physical source being to ensure that even when the total liquid volume is reduced to a critical state of 10.0mL, the solid salt still provides a substrate concentration of 3.0mol / L after dissolution. The safety redundancy factor was set between 1.1 and 1.3 based on the measured sealing pressure of the digestion tube at 200℃. During feeding, the above calibration parameters were input into the controller, and calculations were performed based on the mass of the gold ore to be tested, the mass percentage of sulfur, and the mass percentage of iron. This logic, based on the semi-quantitative scanning data of the gold ore to be tested, identified the main interfering components consuming the oxidant and complexing agent, namely sulfur and iron, and set the mass m of the solid ammonium chloride... (NH4Cl) Set as a function that satisfies the following stoichiometric constraints.

[0035] Specifically, the mass m of solid ammonium chloride NH4Cl Calculations and feeding must be performed according to the formula to ensure that, under the extreme conditions of high-temperature digestion, the liquid phase always maintains sufficient thermodynamic potential energy to suppress the dissociation of silver chloride: m NH4Cl =k⋅(α⋅w S +β⋅w Fe +γ)⋅m ore Where, m ore For the sampling quality of the gold ore to be tested, w S with w FeThese represent the mass percentages of sulfur and iron in the ore, respectively; α is the sulfur consumption coefficient, ranging from 0.08 to 0.12, used to compensate for the loss of volatile chlorine during sulfide oxidation; β is the iron complexation compensation coefficient, ranging from 0.03 to 0.05, used to pre-set the amount of chlorine occupied by chlorine complexes formed by iron ions; γ is the basic molten salt construction constant, fixed at 1.5, used to ensure the formation of the basic framework of the molten salt medium; k is the safety redundancy factor, ranging from 1.1 to 1.3. The feed amount calculated by this formula can offset the chemical competition of the high-sulfur and high-iron matrix for effective chloride ions, ensuring that the concentration of free chloride ions C in the system remains constant when the liquid phase volume shrinks to the critical point. Cl - The complexation equilibrium constraint shown in the formula still applies: ,in, To estimate the total concentration of silver ions, K sp K is the solubility product constant of silver chloride at 190℃. instability η is the cumulative instability constant of the silver tetrachlorotrioxide complex, and η is the activity coefficient correction value under high temperature mixed acid system. This inequality demonstrates the physical inevitability of the 2.5 mol / L threshold in the aforementioned examples from a thermodynamic perspective. Only when the concentration of free chloride ions exceeds this critical value can the reaction rate of the formation of the silver tetrachlorotrioxide complex completely suppress the growth rate of silver chloride crystal nuclei in terms of kinetics.

[0036] To eliminate errors caused by operators' subjective judgment of liquid phase volume during the second-stage high-temperature digestion process, this embodiment specifies that rheological phase transition is used as the objective physical criterion for terminating heating. When the system temperature is maintained at 190°C, as the free acid volatilizes, the reaction system will undergo a transition from a boiling liquid phase to a viscous molten salt phase. The operating procedure clearly stipulates that when the foam on the liquid surface at the bottom of the digestion container changes from rapidly bursting large bubbles to fine microbubbles with a residence time of more than 2 seconds, and the liquid phase exhibits laminar flow characteristics similar to glycerol, it indicates that the system has successfully constructed a stable acidic molten salt-high boiling point phase. In an acid-coupled medium environment, the solid ammonium chloride has reached a supersaturated dissolution equilibrium in a molten or near-molten state, forming a microscopic ion cage effect for silver ions. Once this rheological characteristic is observed, heating is immediately stopped and subsequent cooling and volume adjustment steps are performed. This ensures thorough removal of sparingly soluble minerals while minimizing analyte thermal volatilization loss or salt caking due to excessive evaporation. With this procedure, even for extreme mineral samples with sulfur content as high as 35%, the silver spike recovery rate can still be stably maintained above 99.0%, with a relative standard deviation controlled within 0.8%.

[0037] Example 4: This example addresses the potential data consistency risks that the detection process may encounter in different laboratory environments and during long-term operation. It establishes a standardized on-site pre-calibration and dynamic baseline maintenance procedure. To ensure that the dual internal standard calibration system maintains constant signal compensation performance under different ambient temperatures, humidity levels, and electromagnetic interference levels, this procedure stipulates that an internal standard response factor stability test be performed before each batch of formal testing. This is achieved by continuously injecting blank solutions containing yttrium and scandium internal standards at least 10 times, and artificially introducing gradient-changing plasma power perturbations, such as ±5% power fluctuations. The emission intensity response curve of the internal standard elements is monitored in real time. If the signal response ratio R of scandium to yttrium is... Sc / Y If the relative standard deviation (RSD) exceeds 0.5%, initiate the matching network adaptive calibration procedure for the RF generator, or adjust the atomizer pressure to optimize aerosol delivery efficiency until R... Sc / Y Returning to the preset stable range ensures that the internal standard system has a linear and predictable transfer function in response to physical disturbances, thereby eliminating systematic errors caused by equipment state drift. For plasma torch drift caused by high-salt matrices, a dynamic internal standard response monitoring mechanism is used to implement closed-loop control of the signal acquisition process. The intensity ratio of the two internal standard spectral lines, scandium 361.383 nm and yttrium 371.029 nm, is set as a real-time monitoring variable. If the relative standard deviation of this ratio exceeds the 0.5% control threshold for three consecutive scans, it is determined that the atomization efficiency has shifted nonlinearly, automatically triggering the sample introduction system cleaning program or prompting a check for salt accumulation in the central tube. The monitoring logic limits instrument state fluctuations to the linear range that the mathematical model can correct. Through the synergistic effect of physical maintenance and algorithm compensation, systematic test errors are eliminated.

[0038] Furthermore, to address the issue of fluctuations in the effective chlorine release rate caused by batch variations of solid ammonium chloride during long-term operation, this procedure introduces an offline calibration mechanism for chlorine source release kinetics. Before replacing different batches of solid ammonium chloride raw materials, samples must be taken for micro-simulated digestion experiments. The decay curve of chloride ion concentration in the liquid phase during the high-temperature stage is monitored in real time using potentiometric titration. The measured decay rate v of chloride ion concentration is then used to determine the effective chlorine release rate. Cl The effective chlorine release coefficient λ of the batch of raw materials is calculated by fitting the standard attenuation model in the benchmark database. The safety redundancy factor k in the above feeding formula (1) is finely adjusted and corrected using the coefficient λ to ensure that the actual feeding amount can accurately compensate for the release rate deviation caused by the difference in crystal form or purity of the raw materials. This offline calibration mechanism constructs a closed-loop raw material quality control loop, which ensures the reproducibility and long-term stability of the acidic molten salt environment construction process from the source.

[0039] Example 5: This example provides a standardized engineering calibration and system baseline construction procedure for new laboratories or when changing core reagent batches, to eliminate analytical errors caused by differences in equipment characteristics and fluctuations in the physical properties of raw materials. The first step of the procedure is to construct a particle size-release rate correlation spectrum of solid ammonium chloride. This step is carried out using a constant-temperature microreactor equipped with an online conductivity monitoring module. Solid ammonium chloride with different mesh sizes (e.g., 100-120 mesh, 120-150 mesh, 150-200 mesh) is added to a simulated acidic molten salt medium at 190°C. The conductivity change rate Δκ / Δt is recorded with a sampling period of 10 seconds. This change rate is linearly positively correlated with the chloride ion release rate. By plotting a standard curve of particle size distribution-release rate, the optimal particle size range that meets the kinetic requirements of the formula is determined to be 120 mesh to 150 mesh. For newly purchased raw materials, only one particle size distribution sieving test is required. The release behavior can be predicted based on this spectrum and the feed amount can be fine-tuned without repeating time-consuming chemical calibration.

[0040] To quantify the masking failure boundary of a high-antimony matrix and establish a graded response mechanism, this embodiment performed a critical load pressure test for interfering elements. A series of simulated digestion solutions with a constant silver content (10 mg / L) but progressively increasing antimony content (0.1% to 2.0%) were prepared. Tartaric acid was added according to the above proportions, and after standing for 24 hours, the silver loss in the precipitate was determined using the dimethylglyoxime gravimetric method. The test data showed that when the antimony content exceeded 1.2%, even with excess tartaric acid, the silver recovery rate still decreased sharply, indicating the failure of the single masking mechanism. Therefore, this procedure sets an antimony content of 1.0% as the process diversion threshold: when the semi-quantitative scan shows that the antimony content is below this threshold, the conventional masking process is executed; once this threshold is exceeded, pre-oxidation-volatilization compensation is automatically triggered. The procedure extends the heating time and adds hydrobromic acid in the low-temperature stage, and uses the high volatility of antimony pentabromide to remove part of the antimony matrix in advance, thereby pulling the residual antimony amount back to the effective masking range of tartaric acid; for the acquisition and application of semi-quantitative scanning data, this procedure stipulates that energy dispersive X-ray fluorescence spectrometer (EDXRF) is used as the pre-screening terminal. In order to ensure the accurate matching of scanning data and feeding formula (1), an EDXRF-ICP joint calibration curve is established. Twenty representative high-sulfur and high-iron gold ore samples are selected, and the sulfide intensity value is determined by EDXRF and the accurate value of sulfide is determined by ICP-OES. The correction equation is established by least squares regression. In daily detection, the original intensity value output by EDXRF is corrected by this equation and used as w S and w Fe By inputting the feeding model, the relative error of the ammonium chloride feeding amount is controlled within ±5%. This procedure integrates physical property control, chemical interference classification and processing, and data flow interface standardization, thus constructing a quality assurance system for the entire process.

[0041] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A process for detecting gold and silver grade in gold ore, characterized in that, Includes the following steps: Step 101: Add the gold ore to be tested and the digestion reagent consisting of nitric acid, hydrochloric acid, hydrofluoric acid and solid ammonium chloride to the digestion container to establish the initial detection reaction system; Step 102: Execute a two-stage gradient heating program: In the first stage from 100℃ to 120℃, the free radicals released by the reverse aqua regia system are used to oxidize the sulfides and organic carbon in the gold ore to be tested; In the second stage from 180℃ to 200℃, the supersaturated state of solid ammonium chloride in the liquid phase is maintained to construct a coupling medium environment between acidic molten salt and high-boiling-point acid, and the silver ions released from the gold ore to be tested are locked into a tetrachlorosilver complex state by using the thermodynamic chlorine anchoring mechanism, thus blocking the nucleation path of silver chloride crystal nuclei; Step 103: In the initial detection reaction system, an inorganic oxyacid containing phosphate and tartaric acid as an organic multidentate ligand are introduced. The affinity of phosphate with the ferric ions in the initial detection reaction system is used to generate an inner-orbital complex in situ, which suppresses the background interference of iron spectral lines. Tartaric acid is used to chelate with antimony and tin elements in the gold ore to be tested, which produces a steric stabilizing effect to isolate antimony and tin elements and suppress their hydrolysis reaction during the volume dilution stage. Step 104: After adjusting the volume of the processed liquid phase, collect the atomic emission spectrum signal and calculate the gold and silver grades based on the characteristic peak intensity of the atomic emission spectrum signal.

2. The process for detecting gold and silver grade in gold ore according to claim 1, characterized in that, In step 102, by maintaining the chloride ion concentration C in the coupling medium environment Cl - Satisfies the following relationship: C Cl -≥2.5mol / L; where C Cl - This is the initial detection reaction system after the chloride ion molar concentration is dynamically adjusted as the liquid phase shrinks during the second stage; the coupling medium environment uses the high-temperature solubility characteristics of solid ammonium chloride to offset the concentration decrease caused by the volatilization of the chloride source, and is used to maintain the chloride ion chemical potential under the condition of liquid phase volume reduction.

3. The process for detecting gold and silver grade in gold ore according to claim 1, characterized in that, In step 101, the ratio of the added mass of solid ammonium chloride to the sampled mass of the gold ore to be tested is 2:1 to 3:

1.

4. The process for detecting gold and silver grade in gold ore according to claim 1, characterized in that, In step 102, the temperature holding time in the second stage is 30 to 60 minutes.

5. The process for detecting gold and silver grade in gold ore according to claim 1, characterized in that, In step 103, the inorganic oxyacid is phosphoric acid, and the volume fraction of phosphoric acid in the liquid phase after volume adjustment is 2% to 5%.

6. The process for detecting gold and silver grade in gold ore according to claim 1, characterized in that, In step 104, an inductively coupled plasma atomic emission spectrometer is used to acquire atomic emission spectral signals. The wavelengths for measuring gold and silver are 242.795 nm for gold and 328.068 nm for silver.

7. The process for detecting gold and silver grade in gold ore according to claim 1, characterized in that, In step 103, tartaric acid blocks the pathway of adsorbing silver tetrachlorotrioxide complex by encapsulating antimony and tin metal cations, thus maintaining the physical homogeneity of the initial detection reaction system after volume dilution.

8. The process for detecting gold and silver grade in gold ore according to claim 1, characterized in that, In step 101, the sample size of the gold ore to be tested is 10g to 25g.

9. The process for detecting gold and silver grade in gold ore according to claim 1, characterized in that, In step 101, the volume ratio of nitric acid, hydrochloric acid, and hydrofluoric acid is 1:3:1.

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