1. A method for analyzing and judging a key mineral phase for occurrence of heavy metals in industrial solid waste is characterized by comprising the following steps:

s1, carrying out heavy metal element content determination on the heavy metal solid waste to be detected, and obtaining the content of P types of heavy metal elements to be determined existing in the heavy metal solid waste to be detected;

s2, carrying out N concentration gradient dissociation determination on the heavy metal solid waste to be determined under the same dissociation condition, and obtaining the dissociation degree of the heavy metal element to be determined under N different concentration gradientsD is said_ijRepresents the dissociation degree of the heavy metal element j to be determined in the ith concentration gradient dissociation determination,，i=1,2,3,...,N，j=1,2,...,P；

s3, carrying out quantitative analysis on the mineral phases of the dissociated solid residues dissociated in the step S2 to obtain the relative content W of each mineral phase in M mineral phases of the heavy metal solid waste to be detected_ikThen according to the formulaCalculating the degree of dissociation of each of the mineral phases(ii) a Wherein k =1,2, 3.., M, l_ikRepresents the degree of dissociation of mineral phase k in the ith concentration gradient assay, W_0kThe mass fraction m of the mineral phase k under the initial condition of the heavy metal solid waste to be detected₀Is the initial sample mass m of the heavy metal solid waste to be measured_iAmount of dissociated solid residue after the i-th concentration gradient measurement, W_ikMass fraction of mineral phase k in the dissociated solid residue after the ith concentration gradient measurement;

s4 according to the formulaSolving to obtain the heavy metal elementThe proportion of the occurrence distribution of the elements in the mineral phase，；

And S5, accumulating the occurrence proportion of the heavy metal element j in the mineral phase from high to low, and determining the mineral phase with the accumulation occurrence proportion exceeding a preset accumulation threshold as the occurrence key mineral phase of the heavy metal element j.

2. The method of claim 1, wherein d is_ijIs calculated by the formula including，Is the mass fraction of the heavy metal element j under the initial condition of the heavy metal solid waste to be detected,the concentration of the heavy metal element j in the dissociation solution after the ith concentration gradient measurement,the volume of the dissociation solution after the i-th concentration gradient was determined.

3. The method according to claim 2, wherein before the step S2, the method further comprises performing a pre-cleaning treatment on the heavy metal solid waste to be tested; wherein, theIs calculated in a manner thatWherein, in the step (A),the mass fraction of the heavy metal element j in the heavy metal solid waste to be detected which is not subjected to pre-cleaning,the quality of the heavy metal solid waste to be tested which is not subjected to pre-cleaning,for the quality of the heavy metal solid waste to be detected after pre-cleaning,the concentration of the heavy metal element j in the post-cleaning liquid of the heavy metal solid waste to be detected which is not pre-cleaned,the volume of the heavy metal solid waste cleaning solution to be detected is the volume of the pre-cleaned heavy metal solid waste cleaning solution.

4. The method of claim 1, wherein the pre-washing step comprises: taking 0.1mol/L ammonium acetate solution with pH =7.0 as a pre-cleaning reagent, and mixing the heavy metal solid waste to be detected with 0.1mol/L ammonium acetate solution with pH =7.0 according to a liquid-solid ratio of 10: 1 (L/kg), horizontally oscillating for 1-2 h at 15-35 ℃, and centrifuging the obtained solution for 3-10 min at 6000-10000 rpm to obtain a cleaning solution and the pre-cleaned heavy metal solid waste to be detected; and determining the content of heavy metal elements in the cleaning solution, and performing ore phase quantitative analysis on the pre-cleaned heavy metal solid waste to be detected.

5. The method according to claim 1, wherein the step S1 is preceded by the step of pretreating the heavy metal solid waste to be tested: and (3) drying the sample of the heavy metal solid waste to be detected at 60-105 ℃ in air, and grinding the dried sample to sample powder below 200 meshes.

6. The method of claim 1, wherein the step of performing N concentration gradient dissociation measurements under the same dissociation conditions comprises: under the action of the same time and an external field, performing nonspecific dissociation on the solid waste in N concentration gradient acid solutions, and determining the content of heavy metal elements in the dissociated solution; wherein the acid solution is nitric acid: the mass ratio of hydrochloric acid is 1: 3, mixed acid; and (3) dissociation liquid-solid ratio of 8-12: 1 (L/kg), the temperature is 15-35 ℃, and the dissociation time is 1-2 h; the external field effect comprises ultrasonic waves with the ultrasonic frequency of 20 kHz-40 kHz and the power of 200- & lt 500 & gt W.

7. The method according to claim 6, wherein the number of N is equal to the number M of mineral phases of the heavy metal solid waste to be detected, and the hydrogen ion concentration of the acid solution in the N concentration gradient dissociation assays is in a range of 0-12 mol/L.

8. The method of claim 1, wherein the step of quantitatively analyzing the mineral phases comprises: and obtaining an X-ray diffraction pattern through X-ray diffraction analysis, and determining the relative content of all mineral phases in the dissociated solid residue based on a mode of standard Rietveld full-spectrum fitting refinement, wherein the mineral phases which are not included in the dissociated solid residue are selected as internal standard substances, and the internal standard substances comprise aluminum oxide or zinc oxide.

9. The method of claim 1, wherein the predetermined cumulative threshold is 80% to 95%.

10. The method according to any one of claims 1 to 9, wherein the method for measuring the content of the heavy metal elements is one or any combination of inductively coupled plasma emission spectroscopy, atomic absorption spectroscopy, inductively coupled plasma mass spectrometry and atomic fluorescence spectroscopy.

Background

Industrial solid wastes are very liable to cause various environmental pollutions, and among them, the pollution influence caused by heavy metal industrial solid wastes is the worst. Therefore, rational disposal of industrial solid wastes containing heavy metals is becoming of great importance.

The reasonable treatment and disposal of the heavy metal industrial solid waste are mainly to carry out systematic analysis on occurrence states of heavy metals in the industrial solid waste. At present, the commonly used occurrence state determination method in the environmental field is mainly a Tessier five-step continuous extraction method and a BCR three-step continuous extraction method. These two methods were originally developed for the detection of the heavy metal forms in river sediments and soils and were then applied to the research on solid wastes, however, in practice the rationality of this investigator's spontaneous migratory application was not verified due to the lack of standard reference substances for solid wastes. Secondly, Tessier continuous extraction divides heavy metals into 5 binding forms: namely, an ion exchange state, a carbonate bound state, an iron (manganese) oxide bound state, an organic matter and sulfide bound state, and a residue state, and the BCR continuous extraction method separates heavy metals into an acid extractable state, a reducible state, an oxidizable state, and a residue state. However, the two methods can only summarize occurrence states of heavy metals into several types with the same or similar chemical properties, quantitative occurrence information of heavy metals in specific mineral phases cannot be known, and the design of increasingly refined and customized industrial solid waste treatment scheme cannot be met. In addition, due to the inherent defect of the continuous extraction operation, each step of operation can only be started after the previous step of operation is completed, and the experimental period is long.

Therefore, there is a need to develop a new method for analyzing and determining the occurrence key mineral phases of heavy metals in industrial solid waste, so as to accurately and reliably quantify the occurrence proportion of heavy metals in each mineral phase and determine the occurrence key mineral phases of heavy metals which affect the selection of treatment and disposal technology.

Disclosure of Invention

The invention mainly aims to provide an analysis and judgment method for a heavy metal occurrence key mineral phase in industrial solid waste, and aims to solve the technical problems that a representation method for the heavy metal occurrence key mineral phase in the industrial solid waste is complex and cannot quantify in the prior art.

In order to achieve the aim, the invention provides a method for analyzing and judging a key mineral phase for occurrence of heavy metals in industrial solid waste, which comprises the following steps:

s1, carrying out heavy metal element content determination on the heavy metal solid waste to be detected, and obtaining the content of P types of heavy metal elements to be determined existing in the heavy metal solid waste to be detected;

s2, carrying out N concentration gradient dissociation determination on the heavy metal solid waste to be determined under the same dissociation condition, and obtaining the dissociation degree of the heavy metal element to be determined under N different concentration gradientsD is said_ijRepresents the dissociation degree of the heavy metal element j to be determined in the ith concentration gradient dissociation determination,，i=1,2,3,...,N，j=1,2,...,P；

s3, carrying out quantitative analysis on the mineral phases of the dissociated solid residues dissociated in the step S2 to obtain the relative content W of each mineral phase in M mineral phases of the heavy metal solid waste to be detected_ikThen according to the formulaCalculating the degree of dissociation of each of the mineral phases(ii) a Wherein k =1,2, 3.., M, l_ikRepresents the degree of dissociation of mineral phase k in the ith concentration gradient assay, W_0kThe mass fraction m of the mineral phase k under the initial condition of the heavy metal solid waste to be detected₀Is the initial sample mass m of the heavy metal solid waste to be measured_iAmount of dissociated solid residue after the i-th concentration gradient measurement, W_ikMass fraction of mineral phase k in the dissociated solid residue after the ith concentration gradient measurement;

s4 according to the formulaSolving to obtain the occurrence distribution proportion of the heavy metal elements in the mineral phase，；

And S5, accumulating the occurrence proportion of the heavy metal element j in the mineral phase from high to low, and determining the mineral phase with the accumulation occurrence proportion exceeding a preset accumulation threshold as the occurrence key mineral phase of the heavy metal element j.

Further, d is_ijIs calculated by the formula including，Is the mass fraction of the heavy metal element j under the initial condition of the heavy metal solid waste to be detected,the concentration of the heavy metal element j in the dissociation solution after the ith concentration gradient measurement,the volume of the dissociation solution after the i-th concentration gradient was determined.

Further, before the step S2, pre-cleaning the heavy metal solid waste to be detected; wherein, theIs calculated in a manner thatWherein, in the step (A),the mass fraction of the heavy metal element j in the heavy metal solid waste to be detected which is not subjected to pre-cleaning,the quality of the heavy metal solid waste to be tested which is not subjected to pre-cleaning,for the quality of the heavy metal solid waste to be detected after pre-cleaning,the concentration of the heavy metal element j in the post-cleaning liquid of the heavy metal solid waste to be detected which is not pre-cleaned,the volume of the heavy metal solid waste cleaning solution to be detected is the volume of the pre-cleaned heavy metal solid waste cleaning solution.

Further, the pre-washing step comprises: taking 0.1mol/L ammonium acetate solution with pH =7.0 as a pre-cleaning reagent, and mixing the heavy metal solid waste to be detected with 0.1mol/L ammonium acetate solution with pH =7.0 according to a liquid-solid ratio of 10: 1 (L/kg), horizontally oscillating for 1-2 h at 15-35 ℃, and centrifuging the obtained solution for 3-10 min at 6000-10000 rpm to obtain a cleaning solution and the pre-cleaned heavy metal solid waste to be detected; and determining the content of heavy metal elements in the cleaning solution, and performing ore phase quantitative analysis on the pre-cleaned heavy metal solid waste to be detected.

Further, before the step S1, the method further includes a step of pretreating the heavy metal solid waste to be detected: and (3) drying the sample of the heavy metal solid waste to be detected at 60-105 ℃ in air, and grinding the dried sample to sample powder below 200 meshes.

Further, the step of performing N concentration gradient dissociation assays under the same dissociation conditions comprises: under the action of the same time and an external field, performing nonspecific dissociation on the solid waste in N concentration gradient acid solutions, and determining the content of heavy metal elements in the dissociated solution; wherein the acid solution is nitric acid: the mass ratio of hydrochloric acid is 1: 3, mixed acid; and (3) dissociation liquid-solid ratio of 8-12: 1 (L/kg), the temperature is 15-35 ℃, and the dissociation time is 1-2 h; the external field effect comprises ultrasonic waves with the ultrasonic frequency of 20 kHz-40 kHz and the power of 200- & lt 500 & gt W.

Further, the number of N is equal to the number M of mineral phases of the heavy metal solid waste to be detected, wherein the hydrogen ion concentration range of the acid solution in the N concentration gradient dissociation determination is 0-12 mol/L.

Further, the step of quantitative analysis of mineral phases comprises: and obtaining an X-ray diffraction pattern through X-ray diffraction analysis, and determining the relative content of all mineral phases in the dissociated solid residue based on a mode of standard Rietveld full-spectrum fitting refinement, wherein the mineral phases which are not included in the dissociated solid residue are selected as internal standard substances, and the internal standard substances comprise aluminum oxide or zinc oxide.

Further, the preset cumulative threshold value is 80% -95%.

Further, the method for measuring the content of the heavy metal elements is one or any combination of more of inductively coupled plasma emission spectrum, atomic absorption spectrum, inductively coupled plasma mass spectrum and atomic fluorescence spectrum.

In the invention, multidimensional information of coupled experimental analysis and instrument characterization is used for carrying out N concentration gradient dissociation measurement on the heavy metal solid waste to be detected under the same dissociation condition, obtaining the dissociation degree of the heavy metal element to be determined under N different concentration gradients, carrying out mineral phase quantitative analysis on dissociated solid residues to obtain the relative content of each mineral phase in M mineral phases of the heavy metal solid waste to be detected, then solving to obtain the occurrence distribution proportion of the heavy metal element in the mineral phases, accumulating the occurrence proportion of the heavy metal element in the mineral phases from high to low, and determining the mineral phase of which the occurrence proportion exceeds a preset accumulation threshold as the occurrence key mineral phase of the heavy metal element. The method for analyzing and judging the occurrence key mineral phases of the heavy metals is simple, convenient, rapid, efficient and accurate, realizes accurate analysis of the occurrence states of the heavy metals in the industrial solid waste, comprehensively judges the occurrence key mineral phases of the heavy metals, and provides a refined technical support for selection of treatment and disposal technologies of the industrial solid waste.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a flow chart of the method for analyzing and determining the key mineral phases in the occurrence of heavy metals in industrial solid waste according to the present invention;

FIG. 2 is an X-ray diffraction analysis chart of chromium slag in an example.

The purpose, function, features and advantages of the present invention will be further described with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

It should be noted that all the directional indicators (such as the upper and lower … …) in the embodiment of the present invention are only used to explain the relative position relationship, movement, etc. of the components in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.

Moreover, the technical solutions in the embodiments of the present invention may be combined with each other, but it is necessary to be able to be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent, and is not within the protection scope of the present invention.

Referring to fig. 1, a method for analyzing and determining a critical mineral phase occurring in heavy metals in industrial solid waste according to an embodiment of the present invention includes:

s1, carrying out heavy metal element content determination on the heavy metal solid waste to be detected, and obtaining the content of P types of heavy metal elements to be determined existing in the heavy metal solid waste to be detected.

Specifically, the content of the heavy metal elements can be determined qualitatively and then quantitatively, the qualitative method can be X-ray fluorescence spectroscopy, and the quantitative method can be one or any combination of inductive coupling plasma emission spectroscopy, atomic absorption spectroscopy and laser induced breakdown spectroscopy.

Further, before the step S1, the method further includes a step of pretreating the heavy metal solid waste to be detected: and (3) drying the sample of the heavy metal solid waste to be detected at 60-105 ℃ in air, grinding the dried sample to sample powder below 200 meshes, and drying the sample to constant weight.

S2, carrying out N concentration gradient dissociation determination on the heavy metal solid waste to be determined under the same dissociation condition, and obtaining the dissociation degree of the heavy metal element to be determined under N different concentration gradientsD is said_ijRepresents the dissociation degree of the heavy metal element j to be determined in the ith concentration gradient dissociation determination,，i=1,2,3,...,N，j=1,2,...,P。

specifically, the step of performing N concentration gradient dissociation measurements under the same dissociation conditions comprises: under the action of the same time and an external field, performing nonspecific dissociation on the solid waste in N concentration gradient acid solutions, and determining the content of heavy metal elements in the dissociated solution; wherein the acid solution is nitric acid: the mass ratio of hydrochloric acid is 1: 3, mixed acid; and (3) dissociation liquid-solid ratio of 8-12: 1 (L/kg), the temperature is 15-35 ℃, and the dissociation time is 1-2 h; the external field effect comprises ultrasonic waves with the ultrasonic frequency of 20 kHz-40 kHz and the power of 200- & lt 500 & gt W. The method for measuring the content of the heavy metal elements can be one or any combination of inductive coupling plasma emission spectrum, atomic absorption spectrum, inductive coupling plasma mass spectrum and atomic fluorescence spectrum.

Further, d is_ijIs calculated by the formula including，Is the mass fraction of the heavy metal element j under the initial condition of the heavy metal solid waste to be detected,the concentration of the heavy metal element j in the dissociation solution after the ith concentration gradient measurement,the volume of the dissociation solution after the i-th concentration gradient was determined.

Further, before the step S2, pre-cleaning the heavy metal solid waste to be detected; wherein, theIs calculated in a manner thatWherein, in the step (A),the mass fraction of the heavy metal element j in the heavy metal solid waste to be detected which is not subjected to pre-cleaning,the quality of the heavy metal solid waste to be tested which is not subjected to pre-cleaning,for the quality of the heavy metal solid waste to be detected after pre-cleaning,the concentration of the heavy metal element j in the post-cleaning liquid of the heavy metal solid waste to be detected which is not pre-cleaned,is prepared by pre-cleaningAnd (3) the volume of the heavy metal solid waste cleaning solution to be detected.

Further, the pre-washing step comprises: taking 0.1mol/L ammonium acetate solution with pH =7.0 as a pre-cleaning reagent, and mixing the heavy metal solid waste to be detected with 0.1mol/L ammonium acetate solution with pH =7.0 according to a liquid-solid ratio of 10: 1 (L/kg), horizontally oscillating for 1-2 h at 15-35 ℃, and centrifuging the obtained solution for 3-10 min at 6000-10000 rpm to obtain a cleaning solution and the pre-cleaned heavy metal solid waste to be detected; and determining the content of heavy metal elements in the cleaning solution, and performing ore phase quantitative analysis on the pre-cleaned heavy metal solid waste to be detected. The method for measuring the content of the heavy metal elements is one or any combination of more of inductively coupled plasma emission spectrum, atomic absorption spectrum, inductively coupled plasma mass spectrum and atomic fluorescence spectrum; the step of quantitative analysis of the mineral phases comprises: and obtaining an X-ray diffraction pattern through X-ray diffraction analysis, and determining the relative content of all mineral phases in the dissociated solid residue based on a mode of standard Rietveld full-spectrum fitting refinement, wherein the mineral phases which are not included in the dissociated solid residue are selected as internal standard substances, and the internal standard substances comprise aluminum oxide or zinc oxide.

S3, carrying out quantitative analysis on the mineral phases of the dissociated solid residues dissociated in the step S2 to obtain the relative content W of each mineral phase in M mineral phases of the heavy metal solid waste to be detected_ikThen according to the formulaCalculating the degree of dissociation of each of the mineral phases(ii) a Wherein k =1,2, 3.., M, l_ikRepresents the degree of dissociation of mineral phase k in the ith concentration gradient assay, W_0kThe mass fraction m of the mineral phase k under the initial condition of the heavy metal solid waste to be detected₀Is the initial sample mass m of the heavy metal solid waste to be measured_iFor dissociated solid residual substance after determination of ith concentration gradientAmount, W_ikThe mass fraction of mineral phase k in the dissociated solid residue after the i-th concentration gradient was determined.

Specifically, the number of N is equal to the number M of mineral phases of the heavy metal solid waste to be detected, wherein the hydrogen ion concentration range of the acid solution in the N concentration gradient dissociation determination is 0-12 mol/L.

Specifically, the step of quantitative analysis of the mineral phases comprises: and obtaining an X-ray diffraction pattern through X-ray diffraction analysis, and determining the relative content of all mineral phases in the dissociated solid residue based on a mode of standard Rietveld full-spectrum fitting refinement, wherein the mineral phases which are not included in the dissociated solid residue are selected as internal standard substances, and the internal standard substances comprise aluminum oxide or zinc oxide.

S4 according to the formulaSolving to obtain the occurrence distribution proportion of the heavy metal elements in the mineral phase，。

Specifically, the occurrence distribution ratio of the heavy metal elements in the mineral phase can be expressed as:，(ii) a Wherein, each column vector R in R_jRepresenting the occurrence distribution condition of the heavy metal element j on M mineral phases, and reflecting the proportion of the heavy metal element j distributed to the mineral phase k. Therefore, there is the following relationship:r can be solved by the following formula:wherein L is⁺A generalized inverse of the L matrix.

And S5, accumulating the occurrence proportion of the heavy metal element j in the mineral phase from high to low, and determining the mineral phase with the accumulation occurrence proportion exceeding a preset accumulation threshold as the occurrence key mineral phase of the heavy metal element j.

Optionally, in a specific example, the preset accumulation threshold is 80% to 95%. Specifically, the judgment of the heavy metal occurrence key mineral phase is respectively specific to different heavy metals, and specifically may be: referring to the pareto law, after the occurrence distribution proportion of the heavy metal element j in each mineral phase is arranged from high to low, the critical occurrence mineral phase of the heavy metal element j in the solid waste sample can be considered as the first few mineral phases with the cumulative occurrence distribution proportion equal to or more than 80%.

[ examples ] A method for producing a compound

The chromium slag obtained from a chromium salt enterprise in Yunnan is a typical industrial solid waste containing heavy metals. The chromium element is the heavy metal element which is most concerned by pollution control engineering.

A pretreatment step: according to the method, the solid waste is preferably prepared by taking a proper amount of original samples by a quartering method, crushing the samples by a crusher until the samples completely pass through a 200-mesh sieve, then placing the samples in an open beaker, and drying the samples in a blast oven at 105 ℃ for 6 hours until the weight of the samples is constant.

A pre-cleaning step: taking 15.0000 +/-0.005 g of the solid waste, and pre-washing the solid waste by adopting 0.1mol/L ammonium acetate solution with the pH =7.0, wherein the liquid-solid ratio is 10: 1 (L/kg), shaking horizontally on a shaker at 25 ℃ for 1 h. Centrifuging the obtained solution for 10 min at 8000 rpm, washing for three times, diluting the supernatant to 250ml, diluting to a concentration range suitable for ICP-AES detection, and determining the content of heavy metal elements by ICP-AES; the residual solid was placed in an open beaker and dried in a forced air oven at 105 ℃ for 8 hours to constant weight. Wherein the solid waste sample before and after pre-washing is weighed by using an analytical balance to four decimal places.

Concentration gradient dissociation assay: as known to those skilled in the art, the analysis of the content of heavy metal elements in the original sample is generally characterized by strong acid digestion combined with an instrument. In the implementation, the solid waste is preferably digested at 250 ℃ by using an aqua regia-HF-HClO 4 mixed acid system, the volume of the residual clear solution is determined, and after the solution is diluted to a concentration range suitable for ICP-AES detection, the content of heavy metal elements is determined by ICP-AES.

Taking 1.0000 +/-0.005 g of the pre-cleaned sample, and synchronously performing a series of concentration gradient dissociation experiments. Specifically, for convenient operation, the ratio of the amount of the prepared substances is 1: 3, wherein the concentration of hydrochloric acid is 9mol/L, and the concentration of nitric acid is 3 mol/L. Then, required concentration gradients are prepared by dilution operation, and are respectively 0.01mol/L, 0.05mol/L, 0.1mol/L, 0.2mol/L, 0.5mol/L, 1mol/L, 2mol/L, 4mol/L, 6mol/L, 8mol/L, 10mol/L and 12 mol/L.

The basic principle of the concentration gradient design is to ensure that all kinds of mineral phase particles have the chance of completely or almost completely dissociating, and the dissociation degree of the same mineral phase has difference under different concentration experimental conditions, and the gradient experimental number is equal to the mineral phase number, namely N = M = 12. For solid wastes with stronger stability, such as slag and tailings, the gradient design of low-concentration sparsity and high-concentration can be adopted; for solid waste with poor stability, such as chemical precipitation sludge and fly ash, a gradient design of low-concentration dense and high-concentration sparse can be adopted; if the design cannot be determined, the gradient design used in the embodiment is adopted.

The solid waste sample is prepared by mixing the following components in a liquid-solid ratio of 10: 1 (L/kg), and dissociating for 1h under the conditions of 30 kHz ultrasonic wave and 25 ℃. Centrifuging the dissociated solution for 10 min at 8000 rmp, washing residue with 20 ml deionized water for three times, mixing with the supernatant, diluting to 100 ml, and measuring the content of heavy metal elements by ICP-AES. The solid portion was dried for 8 h to constant weight and weighed.

According to the formulaAnd calculating the dissociation degree of the heavy metal element Cr in the sample after pre-cleaning. The method comprises the following specific steps:

TABLE 1 degree of dissociation of heavy metal Cr in the pre-washed samples

In step S4, the dissociation degree of the heavy metal Cr in each concentration gradient experiment (d 1-d 12) can be determined by the formulaSpecifically, the calculation is as follows:

TABLE 2 degree of dissociation of heavy metal Cr in concentration gradient experiments (d 1-d 12)

The dissociated solid residue after dissociation was subjected to quantitative analysis of mineral phase: the quantitative analysis method of mineral phases is X-ray diffraction analysis (XRD), and specifically comprises determining the relative content of all mineral phases (including amorphous phase) by adopting a standard Rietveld full-spectrum fitting refinement mode, and selecting superior pure alpha-Al as an internal standard substance₂O₃Powder, the mixing proportion is 10%. Those skilled in the art know that the Rietveld full-spectrum fitting refinement needs to be established on the basis of XRD fine scanning, and different analysis software can realize the refinement function. In this example, an X-ray diffractometer from Bruker was used, and a fine scan was performed in 5-80 ° range with 0.01 ° step size and 2.5s step size, and the data analysis software was TOPAS.

According to the formulaAnd calculating the dissociation degree of the mineral phase in each concentration gradient dissociation experiment. The method comprises the following specific steps:

TABLE 3 degree of phase dissociation for each concentration gradient dissociation experiment

Calculating the occurrence distribution proportion of the heavy metal elements in the mineral phase: according to the formulaSolving:and L + is a generalized inverse matrix of the L matrix.

Specifically, in matlab, the mineral phase dissociation data is written into a variable L in a matrix form, the heavy metal element dissociation data is written into a variable E in a matrix form, and the R matrix can be solved by making R = pinv (L) E. The results are shown in Table 4.

TABLE 4 proportion of distribution of heavy metal elements in the mineral phase

According to the occurrence key mineral phase judgment method, after the occurrence distribution proportion is arranged from high to low, the heavy metal element Cr is known to be in an amorphous phase and in hydrogarnet (Ca)₃Al_1.54Fe_0.46(OH)₁₂) Calcium iron stone (Ca)₂Fe_1.28Al_0.72O₅) Calcium carbonate (CaCO)₃) The cumulative occurrence distribution ratio over the first 4 phases is 0.8414 (greater than 0.8), the amorphous phase, hydrogarnet (Ca)₃Al_1.54Fe_0.46(OH)₁₂) Calcium iron stone (Ca)₂Fe_1.28Al_0.72O₅) Calcium carbonate (CaCO)₃) And forming a key mineral phase for the heavy metal element Cr in the solid waste.

In the above technical solutions, the above are only preferred embodiments of the present invention, and the technical scope of the present invention is not limited thereby, and all the technical concepts of the present invention include the claims of the present invention, which are directly or indirectly applied to other related technical fields by using the equivalent structural changes made in the content of the description and the drawings of the present invention.