A method for rapid screening of mineralized weathering crust and evaluation of rare earth ore types in the field

Abstract

The present invention discloses a method for rapid screening of mineral-bearing weathering crusts and evaluating the type of rare earth ore in the field. The method first estimates the ionic phase rare earth content in the sample, then performs full-phase rare earth element content analysis, and then eliminates overestimation and underestimation phenomena, sends the screened samples to the laboratory for analysis of the ionic phase rare earth content therein, and uses the obtained analysis results for resource estimation; and then uses the full-phase rare earth element content analysis data to evaluate the type of rare earth ore according to a specific formula. The method of the present invention can effectively solve the overestimation and underestimation phenomena existing in the current field rapid analysis of ionic phase rare earths, and can also use La, Ce, and Y, or La, Ce, Pr, Nd and Y element contents to estimate the total amount of full-phase rare earth in unknown samples, and can roughly estimate the range of ionic phase rare earth content in unknown samples by combining ionic phase rare earth rapid separation technology; and can also determine the rare earth distribution type of the sample; and effectively improve the analysis accuracy and reduce the analysis cost.

Description

Technical Field

[0001] The present invention relates to a method for rapidly screening ore-bearing weathering crust and evaluating rare earth ore types in the field, and specifically to a technical method combination of rapidly screening ore-bearing weathering crust by using ion phase rare earth rapid analysis technology in the field and obtaining light and heavy rare earth element contents by using portable X-ray fluorescence analysis technology to comprehensively evaluate the type of rare earth ore. Background Art

[0002] Ion adsorption type rare earth ore is a new type of exogenous deposit first discovered in Jiangxi, my country in 1969. Rare earth elements are present as hydrated or hydroxyl hydrated ions on the surface of clay minerals in the weathering crust. It has the characteristics of rich reserves, complete rare earth distribution types, easy mining, low cost and good product quality. The deposit is mainly distributed in seven provinces (regions) in China, including Jiangxi, Fujian, Hunan, Guangdong, Guangxi, Yunnan and Zhejiang. At present, it has been discovered in the United States, Russia, Australia, India, South Africa and other countries, but has not yet formed such a large-scale development and utilization in China.

[0003] The rapid analysis technology of ionic rare earths is a semi-quantitative analysis method used in the field to quickly determine whether the weathering crust contains ion-adsorption rare earth ores during the exploration of ionic rare earth ores. The technical process is to use ammonium sulfate as an exchange agent for rare earth ions, and then use oxalic acid or ammonium bicarbonate titration as a simple method to determine whether there are ionic rare earths. The content of oxalic acid or rare earth carbonate after titration is positively correlated with the turbidity of the solution, and the content of ionic rare earths in the sample can be roughly determined. The experimental principle is consistent with the laboratory analysis process, so it is a qualitative + semi-quantitative rapid analysis technology. However, on the one hand, since the parent rocks of the weathering crust containing ion-adsorption rare earth ores are granites, volcanic rocks and metamorphic rocks, these rocks also weather and release substances such as Al in the soil formation process. 3+ , Fe 3+ Mg 2+ , Ca 2+ 、Na + , K + ,RE 3+(Rare earth ions) form hydrated hydroxyl ions in the weathering crust; on the other hand, since this type of deposit is a rare earth element adsorbed in the form of hydrated hydroxyl ions on the surface of clay mineral aggregates composed of halloysite, illite, kaolinite and montmorillonite in the weathering crust, it is impossible to use the naked eye and smell to judge whether the weathering crust contains minerals and the content of ionic rare earths in the field, which is a type of invisible and intangible deposit; in addition, since the formation of this type of deposit is comprehensively controlled by many factors such as the abundance of rare earths in rocks, the degree of structural development, climate, topography and landforms, water, oxygen, carbon dioxide, pH, Eh, temperature, etc., many discontinuous or isolated rare earth ore bodies and weathering crusts without minerals are formed in space. The mixed distribution pattern brings great difficulties to the exploration activities of ion-adsorption rare earth deposits. At present, there is no effective technology and method for detecting this type of deposit. If drilling is used directly, it is easy to waste funds, thereby increasing the geological exploration cost of this type of deposit.

[0004] According to the research of Chi Ruan et al. (Chi Ruan, Tian Jun, "Chemical Metallurgy of Weathering Crust Leaching Rare Earth Minerals", Science Press, 2006.9, p87-89), clay minerals have the adsorption capacity of RE 3+ >Al 3+ >Ca 2+ >Mg 3+ >K 3+ >NH4 + >Na + In addition, clay minerals also have strong adsorption capacity for elements such as Cr, Cd, Pb, Zn, and As. Although the rapid analysis technology of ionic phase rare earth minerals can quickly determine whether the weathering crust sample contains rare earth or how much ionic phase rare earth it contains in the field, due to Al 3+ , Fe 3+ Mg 2+ , Ca 2+ The exchange capacity of plasma is lower than that of rare earth ions RE 3+ , that is, when RE 3+ In the process of being exchanged, Al in the form of hydrated ions 3+ , Fe 3+ Mg 2+ , Ca 2+ The ions are exchanged together by the exchanger, but when oxalic acid or ammonium bicarbonate is titrated, the following two situations usually occur:

[0005] The first one: underestimation phenomenon, when RE in the sample 3+ When they are dominant, these impurity ions consume more oxalic acid or ammonium bicarbonate, which can easily cause the rare earth oxalate or rare earth carbonate content formed during the titration process to be lower than the actual rare earth content in the sample. This is the phenomenon of underestimating the rare earth content in the ionic phase in the sample during the rapid field analysis of ion adsorption-type rare earth mineral exploration.

[0006] The second type: overestimation phenomenon, when RE in the sample 3+ When it is not dominant, that is, there is no ionic rare earth. These impurity ions will preferentially consume more oxalic acid or ammonium bicarbonate, which can easily cause false precipitation during the titration process, and be mistaken for containing high content of oxalate rare earth or carbonate rare earth. In fact, the rare earth in these samples is very low. This is the phenomenon of overestimating the content of ionic rare earth in samples during rapid field analysis.

[0007] However, these two situations often occur in every mining area, especially when there is a lot of kaolin in some samples, it is very easy to have the illusion of high rare earth content (kaolin is mainly aluminum silicate). Under normal circumstances, the occurrence of overestimation will lead to the misidentification of non-ore samples as ore samples, and then send them to the laboratory for analysis, which will lead to unnecessary waste of analysis fees. At the same time, due to overestimation of mineralization, useless projects will be deployed or the ore body will be penetrated and the ore body will continue to be controlled. In actual exploration activities, these are all wastes of manpower and financial resources caused by imperfect technology. Similarly, underestimation will also lead to the fact that there is a mine, but due to underestimation of the quick score, no samples are collected, resulting in the actual ore body being missed, which will directly lead to a reduction in the amount of ore deposit resources. The situation involved here is more complicated. If it is a single project, it will cause the ore body thickness and grade data to decrease; if it is a boundary project, it will directly affect whether this location is the boundary of the ore body, and this situation has the greatest impact. Although this situation can be compensated by subsequent exploration activities, the waste of manpower and funds caused by this is much greater than overestimation. Therefore, in the exploration process of ion adsorption rare earth minerals, these two actual estimation deviation phenomena are unacceptable. It is necessary to develop a technology or method that can effectively control the occurrence of these two phenomena, so as to effectively reduce the exploration cost, make the best use of drilling to obtain more accurate rare earth mineralization information, and reduce the risk of resource reduction due to excessive exploration engineering.

[0008] To address this problem, Chen Ronglian et al. (Chen Ronglian, Pang Lun, Chen Daren, Chen Cui'e. Journal of Jinan University (Natural Science and Medicine Edition), Issue 3, 1989, p57-61) used 10% sulfosalicylic acid (2.0 ml)-acetic acid acetone (1.0 mL) as a combination of Al 3+ Masking agent, remove Al 3+ However, since this process involves the addition of dimethoate orange indicator and titration with standard EDTA solution, the pH needs to be adjusted throughout the process, although it is effective in reducing Al 3+interference, but the efficiency of analysis is still low. Therefore, the method of adding a combined masking agent is also difficult to achieve the purpose of rapid field analysis and accuracy. Then, because oxalic acid is toxic, it is replaced by ammonium carbonate, but because ammonium carbonate is a substance with both acidity and alkalinity, it is necessary to adjust the pH value after ammonium sulfate leaching, and carbonate ions precipitate with Ca, Mg, Fe, Mn, Pb, etc., and at the same time, because of the alkalinity of carbonic acid, it is easy to precipitate with Al, Fe, etc., so the situation is more complicated under field operation conditions, and its process is much more complicated than oxalic acid, so it is not suitable for the analysis and operation of large quantities of samples in the field.

[0009] So far, the method of ammonium sulfate leaching and oxalic acid titration is still used. The main process is to first leaching the samples collected in the field with ammonium sulfate, then titrate with oxalic acid, visually determine the rare earth content in the unknown samples, and then select the samples with rare earth precipitation to send to the laboratory for analysis. However, due to the common presence of the above impurities (Al 3+ , Fe 3+ Mg 2+ , Ca 2+ Such a practice will cause about 15-25% of the samples to be sent to the laboratory for analysis due to the overestimation of the field rapid analysis, which will eventually result in a high proportion of analysis costs in the exploration project. Therefore, how to improve the accuracy of field rapid analysis during the exploration of such rare earth minerals is a problem worth exploring. Exploring an effective, fast and low-cost exploration technology is an urgent problem to be solved in the exploration of such mineral deposits, and it is also an important measure to reduce the analysis cost in the exploration of such mineral deposits.

[0010] With the development of X-ray energy dispersive spectrometers, there are now field instruments that can analyze the three rare earth elements La, Ce, and Y, which provides another feasible technology for exploring and solving the above problems. Liang Shuting (1997) proposed the best measurement conditions for Ce and Y through the linear relationship between 2×Ce+Y and the total amount of rare earths. The results of Ce and Y measured by X-ray fluorescence spectrometer can be directly measured by parameter conversion to determine the total amount of rare earth elements in the sample. This method has a detection limit of 17μg / g and a relative standard deviation of 20%. However, this method is based on the regression relationship obtained from water sediment samples and is not suitable for measuring the rare earth content in ion adsorption type rare earth ores. The main reason is that the rare earth element content in the weathering crust sample does not conform to the chondrite standardization model. In most cases, positive Ce or negative Ce occurs, and the measured results will be slightly higher or lower. Yan Jun et al. (Yan Jun, Gong Xitai. Application of Energy Dispersive X-ray Fluorescence Rapid Determination Device in Rare Earth Analysis, Rare Earth, 1995, 16 (2), p70-76) designed a set of energy dispersive X-ray fluorescence rapid determination device, which can simultaneously determine multiple rare earth elements, but can only determine rare earth elements in liquids, with a detection limit of about 700 μg / kg, and can only be used in high-purity rare earth detection activities. In the process of ion adsorption type rare earth mineral exploration, the rare earth content in the sample is usually high or low, and the device is difficult to play its role under such test conditions. It can be seen that so far, there is no simple, rapid, efficient and accurate ion phase rare earth detection method in the process of ion adsorption type rare earth mineral exploration. Summary of the invention

[0011] The technical problem to be solved by the present invention is to provide a method for rapid screening of mineral-bearing weathering crusts and evaluating the type of rare earth ores in the field. The method can effectively solve the overestimation and underestimation phenomena existing in the current rapid field analysis of ionic phase rare earths, and can also estimate the total amount of all-phase rare earths in unknown samples by using the content of elements such as La, Ce, and Y. Combined with the rapid separation technology of ionic phase rare earths, the range of the content of ionic phase rare earths in unknown samples can be roughly estimated; the rare earth distribution type of the sample can also be determined; the accuracy of the current rapid field analysis technology of ionic phase rare earths can also be increased from the current 50-60% to 95-100%, effectively reducing the analysis cost by 35-40% in the exploration process of ion adsorption type rare earth ores.

[0012] The method for rapid field screening of ore-bearing weathering crust and evaluation of rare earth ore types of the present invention comprises the following steps:

[0013] Step I, estimating the ionic phase rare earth content in the sample: collecting weathering crust samples, leaching with ammonium sulfate solution and then titrating with oxalic acid solution, observing whether the obtained feed solution has a color reaction, measuring the turbidity of the feed solution with a color reaction, and determining the ionic phase rare earth content of each sample according to the corresponding relationship between the turbidity value and the ionic phase rare earth content in the sample in Table 1 below and making records, discarding samples with a turbidity value less than 5, and performing full-phase rare earth content analysis on the remaining samples;

[0014] Table 1: Turbidity and rare earth content interval division table

[0015]

[0016] Step II, full-phase rare earth element content analysis: the sample screened in step I is tested for full-phase rare earth element content and impurity element content by X-ray fluorescence spectrometer, and records are kept; wherein, the full-phase rare earth elements are La, Ce and Y, or La, Ce, Pr, Nd and Y; the impurity elements include Al, Fe, Ca, Mg;

[0017] Step III, eliminate over- and underestimation phenomena: According to the test data of step II, the total amount of all-phase rare earth oxides in the sample is calculated by C3 method or C5 method. When 90% of the total amount of all-phase rare earth oxides in the sample is greater than or equal to 90% of the definition standard of the mine boundary, and 70% of the total amount of all-phase rare earth oxides in the sample is greater than 70% of the definition standard of the mine boundary, the sample is retained and sent to the laboratory for analysis, otherwise it is only kept as a mineralized sample for further evaluation; wherein,

[0018] When the total rare earth elements detected in step II are La, Ce and Y, the total amount of total rare earth oxides in the sample is calculated using the C3 method. The C3 method calculates the total amount of total rare earth oxides in the sample according to the following formula (1):

[0019] TREO (3) =(C La +C Ce +C Y )×k3 (1)

[0020] In formula (1), k3 is 1.7 to 2.0; TREO (3) is the total amount of all-phase rare earth oxides fitted by C3 method, in μg / kg; C La , C Ce and C Y are the contents of rare earth elements La, Ce and Y in the samples, respectively, in μg / kg;

[0021] When the total rare earth elements detected in step II are La, Ce, Pr, Nd and Y, the total amount of total rare earth oxides in the sample is calculated using the C5 method. The C5 method calculates the total amount of total rare earth oxides in the sample according to the following formula (2):

[0022] TREO (5) =(C La +C Ce +C Pr +C Nd +C Y )×k5 (2)

[0023] In formula (2), k5 is 1.2 to 1.4; TREO (5) is the total amount of all-phase rare earth oxides fitted by the C5 method, in μg / kg; C La , C Ce , C Pr , C Nd and C Y are the contents of rare earth elements La, Ce, Pr, Nd and Y in the samples, respectively, in μg / kg;

[0024] Step IV: Send the sample screened out in step III to the laboratory to analyze the ionic phase rare earth content therein according to the ionic phase rare earth analysis method. The obtained analysis result is the true ionic phase rare earth content in the sample, and the analysis result is used for resource estimation;

[0025] Step V: Based on the detection data of step II, the type of rare earth ore is evaluated using the following formula (3) or formula (4); wherein:

[0026] When the full-phase rare earth elements detected in step II are La, Ce and Y, if the following formula (3) is satisfied, the sample is determined to be a heavy rare earth type, otherwise the sample is a light rare earth type;

[0027] 1.5×(C La +C Ce )>C Y (3)

[0028] In formula (3), C La , C Ce and C Y are the contents of rare earth elements La, Ce and Y in the samples, respectively, in μg / kg;

[0029] When the full-phase rare earth elements detected in step II are La, Ce, Pr, Nd and Y, if the following formula (4) is satisfied, the sample is determined to be a medium-heavy rare earth type, otherwise the sample is a light rare earth type;

[0030] (C La +C Ce +C Pr+C Nd +) / C Y ≤2 (4)

[0031] In formula (4), C La , C Ce , C Pr , C Nd and C Y They are the contents of rare earth elements La, Ce, Pr, Nd and Y in the samples respectively, and the unit is μg / kg.

[0032] Step I of the above method specifically comprises the following steps:

[0033] 1) Sampling: Collect weathering crust samples, remove weeds and branches, and set aside;

[0034] 2) Sample dissolution with leaching agent: Accurately weigh a certain amount of sample and place it in a container, add ammonium sulfate solution and mix with the sample, stir to dissolve, then centrifuge and filter, and collect the filtrate;

[0035] 3) Titration: add oxalic acid solution to the filtrate, observe the color change of the feed solution after shaking, measure the turbidity of the feed solution with color reaction, and determine the ionic phase rare earth content of each sample according to the corresponding relationship between turbidity and ionic phase rare earth content in the sample in Table 1 and keep a record, discard the samples with turbidity less than 5 degrees, and analyze the whole phase rare earth content of the remaining samples.

[0036] In the above step 2), the concentration and dosage of the ammonium sulfate solution are the same as those in the prior art. Specifically, its concentration is 3-5w / w%, and the ratio of its dosage to the sample is 1ml:1g.

[0037] In the above step 3), the concentration and amount of the oxalic acid solution are the same as those in the prior art, and its concentration is usually 2-3 w / w%, and its volume ratio to the filtrate is 1:1.

[0038] In step II of the above method, a portable X-ray fluorescence spectrometer is usually used to detect the total rare earth element content and the impurity element content in the sample, such as Niton XL3t 700s, SPECTROSCOUT, etc.). When the instrument is analyzed, the sample amount, sample particle size, test time, etc. are limited according to the requirements of the instrument. Usually, 3 to 5 g of sample is weighed, and the sample particle size is controlled at 40 to 80 meshes. It is placed in the test cup of the X-ray analysis equipment and the sample is measured at 0.06 to 3 kg / cm 2 The sample is compacted with a force, and then the machine is turned on to test the content of all-phase rare earth in the sample. The test time is preferably controlled within 15 to 30 seconds.

[0039] In step III of the above method, the definition standard of the mine boundary is the definition standard of the mine and non-mine in the current standard of rare earth mineral exploration. Here, the current standard refers to DZ / T 0204-2002, in which the mine and non-mine are clearly defined as the content of total rare earth (TREO) in the sample, that is, the total rare earth content in the sample is greater than 500μg / kg. Therefore, the definition standard of the mine boundary in this application is 500μg / kg.

[0040] In step IV of the above method, the current conventional ionic phase rare earth analysis method (such as XB / T619-2015) is used to detect the ionic phase rare earth (REO) content in the sample screened out in step III.

[0041] Compared with the prior art, the present invention is characterized in that:

[0042] 1. By adopting the combination of rare earth rapid field analysis + instrumental analysis technology, the entire operation is simple, fast and accurate. It is faster and simpler than the current analysis method, the equipment is simple and easy to operate, and it is very suitable for field large-scale sample analysis in various exploration stages such as rare earth preliminary investigation, general investigation and detailed investigation.

[0043] 2. By using X-ray fluorescence instrument analysis, a comprehensive comparison of the results from the two occurrence states of total rare earth and ionic rare earth can effectively eliminate the overestimation and underestimation caused by the single sampling rare earth field rapid separation technology, thereby reducing the number of non-mineral samples analyzed and greatly reducing the analysis fee of samples, thereby reducing the investment in exploration costs.

[0044] 3. Since a combination of two technologies is used, the method can be carried out in steps compared to other methods, that is, it can be divided into two processes, wherein step I can be carried out on the day of sample collection, and the subsequent steps can be analyzed intensively at another time, which is incomparable to the existing technology. It can avoid the problem of conflict between analysis work and other work caused by collecting too many or too few samples, and is more flexible and changeable than the existing technology. Such a process is more suitable for the exploration of rare earth mines; at the same time, it can also determine what type of rare earth mine the obtained rare earth mine is, which is beyond the reach of the existing technology.

[0045] 4. At present, the minimum detection limit of field rapid analysis technology is about >100μg / kg, while the detection limit of X-ray fluorescence analyzer for La, Ce, Y, etc. can reach 10μg / kg. After comprehensive judgment, its detection limit can reach 30μg / kg, which has higher detection accuracy than existing technology.

[0046] 5. Due to the use of ion phase analysis technology and full phase analysis technology, the data of the two occurrence states of ion phase and full phase can be obtained for the mineralized samples at the same time, which is not achievable with the existing technology. The data obtained can also reflect the leaching rate data of the mining area, so as to understand the spatial continuity of the ion phase rare earth mineralization in the mining area, which cannot be solved by other current methods. In addition, due to the use of C3 regression prediction method, this method can also be applied to the field rare earth analysis of other geological bodies.

[0047] 6. The samples finally sent to the laboratory by the method described in the present invention are all analyzed for the total amount of all-phase rare earths in the samples. The ionic phase data obtained by the laboratory is always smaller than the full-phase data. Therefore, the results of the method described in the present invention can be used to evaluate the reliability of the laboratory's ionic phase analysis results of the samples. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with specific embodiments to provide a better understanding of the content of the present invention, but the present invention is not limited to the following embodiments.

[0049] The inventor team of this application has found through many years of exploration practice of ion adsorption rare earth ore and statistical analysis of a large number of measured data of similar deposits that in the weathering crust rare earth analysis data of different regions and different rare earth ore types, the linear relationship between 2×Ce+Y (referred to as C2 method, see formula (5)) in the total phase and ionic phase rare earth components and the total amount of rare earth is weak, the correlation is unstable, and the regression coefficient R 2 The linear relationship between La+Ce+Y (referred to as C3 method, see formula (1)) and the total amount of rare earth is stronger, and the regression coefficient R 2 The range is about 0.81 to 0.97 (see Table 3). Through the measured data of multiple mining areas and the rare earth data in different geological bodies, it is verified that there is a strong linear correlation between La+Ce+Y and the total amount of rare earth, and this relationship is relatively stable. Whether it is ionic phase or full phase data, there is a strong linear correlation between the C3 method and the total amount of rare earth.

[0050] Table 2: Regression parameters and error evaluation table of the total amount of rare earth predicted by the C2 method for ion adsorption rare earth ore

[0051]

[0052]

[0053] Table 3: Regression parameters and error evaluation table of the total amount of rare earth predicted by the C3 method for ion adsorption rare earth ore

[0054]

[0055] Considering that the content range of La, Ce and Y in the samples is relatively large, in order to ensure consistency with the actual rare earth content of the samples, the influence of the slope distance on the total amount of rare earth is eliminated (when there is a slope distance, the fitted rare earth content will have a negative value, which is not allowed), so a linear correlation regression passing through the origin is adopted, as shown in formula (5).

[0056] C2 method: TREO (2) =2×C Ce +C Y (5)

[0057] In formula (5), TREO (2) is the total amount of all-phase rare earth oxides fitted by C2 method, in μg / kg; C Ce and C Y They are the contents of rare earth elements La and Y in the samples, respectively, and the unit is μg / kg.

[0058] C3 method: TREO (3) =(C La +C Ce +C Y )×k3 (1)

[0059] In formula (1), k3 is 1.7 to 2.0; TREO (3) is the total amount of all-phase rare earth oxides fitted by C3 method, in μg / kg; C La , C Ce and C Y They are the contents of rare earth elements La, Ce and Y in the samples respectively, and the unit is μg / kg.

[0060] Similarly, the C5 method is constructed. That is, when the detected full-phase rare earth elements are La, Ce, Pr, Nd and Y, the C5 method is used to calculate the total amount of full-phase rare earth oxides in the sample. The C5 method calculates the total amount of full-phase rare earth oxides in the sample according to the following formula (2):

[0061] C5 method: TREO (5) =(C La +C Ce +C Pr +C Nd +C Y )×k5 (2)

[0062] In formula (2), k5 is 1.2 to 1.4; TREO (5) is the total amount of all-phase rare earth oxides fitted by the C5 method, in μg / kg; C La , C Ce , C Pr , C Nd and C YThey are the contents of rare earth elements La, Ce, Pr, Nd and Y in the samples respectively, and the unit is μg / kg.

[0063] Since the instrumental analysis gives two groups of rare earth elements, La, Ce, (Pr, Nd), and Y, namely the light rare earth element group: La, Ce, or La, Ce, Pr, Nd; the heavy rare earth element group: Y, according to the general distribution composition of ion adsorption type rare earth ores, under normal circumstances, the distribution type of rare earth in the sample can be roughly determined (see Table 4). The basis for the determination is the following formula (3) or formula (4), where:

[0064] When the detected full-phase rare earth elements are La, Ce and Y, if the following formula (3) is satisfied, the sample is determined to be a heavy rare earth type, otherwise the sample is a light rare earth type;

[0065] 1.5×(C La +C Ce )>C Y (3)

[0066] In formula (3), C La , C Ce and C Y are the contents of rare earth elements La, Ce and Y in the samples, respectively, in μg / kg;

[0067] When the detected full-phase rare earth elements are La, Ce, Pr, Nd and Y, if the following formula (4) is satisfied, the sample is judged to be a medium-heavy rare earth type, otherwise the sample is a light rare earth type;

[0068] (C La +C Ce +C Pr +C Nd +) / C Y ≤2 (4)

[0069] In formula (4), C La , C Ce , C Pr , C Nd and C Y They are the contents of rare earth elements La, Ce, Pr, Nd and Y in the samples respectively, and the unit is μg / kg.

[0070] The validity checks of the above methods are shown in Table 4, which respectively used the ionic phase rare earth ore standard samples independently developed by China Nonferrous Guilin Mineral Geology Research Institute Co., Ltd. in 2017 (referred to as 2017 Mineral Geology Institute Standard Samples, namely Guangxi G1, Guangxi G2 and Jiangxi J1); the ionic phase rare earth ore standard samples independently developed by China Nonferrous Guilin Mineral Geology Research Institute Co., Ltd. in 2019 (referred to as 2019 Mineral Geology Institute Standard Samples, namely G1, G2 and G3); the ionic phase rare earth ore standard samples independently developed by the Guangxi Zhuang Autonomous Region Geology and Mineral Testing Research Center (referred to as Guangxi Standard Samples, namely Guangxi No. 1 Standard Sample, Guangxi No. 2 Standard Sample and Guangxi No. 3 Standard Sample); and the National Rare Earth Ore Composition Analysis Standard Materials (referred to as National Standard Samples, namely GBW07158, GBW07160 and GBW07161), totaling 12 samples.

[0071] Table 4: Method validity test list

[0072]

[0073]

[0074] In the table, the L(3) prediction type represents the result of evaluating the rare earth ore type according to formula (3) in the method described in the present invention, and the L(5) prediction type represents the result of evaluating the rare earth ore type according to formula (4) in the method described in the present invention.

[0075] As can be seen from Table 4, the total amount of rare earth predicted by the method of this application is consistent with the recommended value of the standard sample, and its rare earth ore type judgment C5 method is more accurate and reliable than the C3 method. It can be seen that the use of a portable X-ray fluorescence spectrometer + field fast separation technology combination can accurately determine the content of ionic phase rare earth and total phase rare earth in unknown samples, thereby achieving rapid and accurate field judgment of the mineralization of samples. This technical combination has advantages that are beyond the reach of current colorimetry and titration methods, and can greatly improve the efficiency of field exploration of such deposits and reduce analysis costs, thereby significantly reducing exploration costs.

[0076] Considering that the X-ray fluorescence spectrometers generally used in the field are not very accurate in testing Pr and Nd, it is usually only necessary to measure La, Ce, and Y to estimate the total amount of rare earths. If more advanced instruments are available, the C5 method is used.

[0077] Practice shows that the method of the present invention has a working efficiency of about 2000 to 5000 pieces / day / person for identifying the rare earth content of samples, and dozens of working groups can be carried out at the same time, and the rare earth ore type judgment is greater than 800 pieces / day / unit. This is currently unachievable by the existing field rapid analysis technology or methods in this field, and has good promotion value. Generally speaking, the C5 method has higher accuracy, and the C5 method is preferred.

[0078] Example 1

[0079] Taking a rare earth mine survey project in Rong County, Guangxi as an example, the samples are actual samples in the survey project, which are taken from the Hercynian cordierite biotite monzogranite in the Dayongshan granite belt in Guangxi. The ore deposit is mainly composed of light rare earths and a few heavy rare earths. The thickness of the weathering crust is 5 to 35m. The samples are taken from the whole weathering layer. The sampling length is 1m. The sampling method is groove sampling. The sample weight is 500g and the number of samples is 46. After sampling, the samples are quickly analyzed according to the following method, and then the screened samples are sent to the laboratory for analysis. The specific implementation process is as follows:

[0080] 1) Sampling: Collect weathering crust samples with a sample weight of ≥500g, remove weeds and branches for subsequent quick separation;

[0081] 2) Sample dissolution with leaching agent: Use a 1 / 1000 balance to weigh 20 g of the sample in 1), place it in a 100 ml beaker, and use a pipette to absorb 20 ml of a pre-prepared 5% ammonium sulfate solution and mix it with the sample;

[0082] 3) Stirring: Place the beaker in 2) under an electric stirrer at 40 to 120 rpm for 5 minutes, then remove and centrifuge for precipitation;

[0083] 4) Centrifugal precipitation: Place the beaker in 3) in a 4-position centrifuge, centrifuge at 2000 g for 2 minutes, then take out and let stand for 30 seconds before filtering;

[0084] 5) Filtration: Use medium-speed filter paper to filter the supernatant in the beaker of 4) into a 30ml graduated conical flask. After filtration, the filtrate should be controlled to 10ml and then titrated with oxalic acid;

[0085] 6) Titration: Select a 2% oxalic acid solution prepared in advance, use a pipette to absorb the oxalic acid solution in a volume ratio of 1:1 and place it in the conical flask in 5). The more rare earth oxalate is generated, the more turbid the solution is. Therefore, a portable turbidity meter is used to measure its turbidity. According to the turbidity value and the corresponding relationship between the turbidity value and the ionic phase rare earth content in the sample in Table 1 below, the ionic phase rare earth content of each sample is determined, and records are kept. Samples with a turbidity value less than 5 (i.e., the ionic phase rare earth is less than 100 μg / kg) are quickly separated, and the remaining samples are sent to step 7) for instrumental analysis;

[0086] Table 1: Turbidity and rare earth content interval division table

[0087]

[0088] 7) All-phase rare earth instrument analysis: Through steps 1) to 6), samples with weak or no mineralization can be quickly diagnosed; rearrange the samples, record the sample numbers, weigh 3 to 5 g of sample from the mineralized sample, control the sample size to 40 to 80 mesh, place it in an X-ray fluorescence analysis plastic cup, and 2 The sample is compacted by the force of the tester, and then the tester is turned on to test the content of all-phase rare earth in the sample. The test time is 15 to 30 seconds. At the same time, elements such as Al, Fe, Ca, and Mg can also be tested. After the test, the content of all-phase rare earth and the content of impurity elements of each sample are sorted out for subsequent analysis and evaluation;

[0089] 8) Elimination of over- and underestimation phenomena: Based on the data analyzed in step 7), the total amount of all-phase rare earth oxides in the sample is calculated according to the following formula (1). When 90% of the total amount of all-phase rare earth oxides in the sample is greater than or equal to 350 μg / kg, and 70% of the total amount of all-phase rare earth oxides in the sample is greater than 350 μg / kg, the sample is retained and sent to the laboratory for analysis. Otherwise, it is only kept as a mineralized sample for further evaluation;

[0090] TREO (3) =(C La +C Ce +C Y )×k3 (1)

[0091] In formula (1), k3 is 1.7 to 2.0; TREO (3) is the total amount of all-phase rare earth oxides fitted by C3 method, in μg / kg; C La , C Ce and C Y are the contents of rare earth elements La, Ce and Y in the samples, respectively, in μg / kg;

[0092] 9) Laboratory analysis: Through steps 1) to 8), samples that have reached the industrial boundary have been quickly and accurately screened out from a large number of samples. After the samples are naturally dried, they are sent to the laboratory to analyze the ionic phase rare earth (REO) in the samples according to the ionic phase rare earth analysis method (XB / T619-2015). The analysis results obtained are the actual rare earth content in the samples, which can be used for resource estimation.

[0093] Through the implementation of the above process, the mineralized sample pieces obtained in this embodiment are finally screened out, and the results are shown in Table 5. In order to further illustrate the screening function of this method in mineralized samples, in this embodiment, we sent all 46 samples participating in the experiment to the laboratory for analysis. The analysis fee for each sample is 160 yuan / piece, the freight is about 1 yuan / piece, and the processing fee is about 15 yuan / piece. Then compare the accuracy of the present invention and the comparison of reducing the analysis fee, and the results are shown in Table 6.

[0094] Table 5: Wild rare earth content in a rare earth mining area in Rong County, Guangxi (μg / kg)

[0095]

[0096]

[0097] In the table, the "Quick Estimate" result is estimated based on the turbidity value according to the corresponding relationship in Table 1, the same below; REO 室内 Refers to the ionic rare earth content in the sample tested in the laboratory according to XB / T619-2015, the same below; TREO 室内 It refers to the total rare earth content in the sample tested in the laboratory according to GB / T 17417.1-2010, the same below; "patent retained sample" refers to whether the sample is retained after eliminating the over- and underestimation phenomena according to the method described in this application, the same below.

[0098] Table 6: Cost efficiency analysis of Example 1 (unit: yuan)

[0099]

[0100] As can be seen from Tables 5 and 6, the screening of samples by the present invention in Example 1 is consistent with the laboratory results, and the accuracy is improved by 28.3% compared with the currently used field quick separation technology, and the cost is reduced from 8096 yuan to 5808 yuan, a cost reduction of 28.3%.

[0101] Example 2

[0102] Taking a rare earth mine survey project in Yulin City, Guangxi as an example, the samples are actual samples in the survey project, which are taken from the Hercynian cordierite biotite monzogranite in the Darongshan granite belt in Guangxi. The ore deposit is mainly composed of light rare earth and a few heavy rare earth. The thickness of the weathering crust is 2 to 40m. The samples are taken from the whole weathering layer. The sampling length is 1m. The sampling method is groove sampling. The sample weight is 500g and the number of samples is 50. After sampling, the samples are quickly analyzed according to the following method, and then the screened samples are sent to the laboratory for analysis. The specific implementation process is as follows:

[0103] 1) Sampling: Collect weathering crust samples with a sample weight of ≥500g, remove weeds and branches for subsequent quick separation;

[0104] 2) Sample dissolution with leaching agent: Use a 1 / 1000 balance to weigh 20 g of the sample in 1), place it in a 100 ml beaker, and use a pipette to absorb 20 ml of a pre-prepared 5% ammonium sulfate solution and mix it with the sample;

[0105] 3) Stirring: Place the beaker in 2) under an electric stirrer at 100 rpm for 2 minutes, then remove and centrifuge for precipitation;

[0106] 4) Centrifugal precipitation: Place the beaker in 3) in a 4-position centrifuge, centrifuge at 10,000-12,000 g for 1 minute, then take out and let stand for 50 seconds before filtering;

[0107] 5) Filtration: Use medium-speed filter paper to filter the supernatant in the beaker of 4) into a 30ml graduated conical flask. After filtration, the filtrate should be controlled to 10ml and then titrated with oxalic acid;

[0108] 6) Titration: Select a pre-prepared 3% oxalic acid solution, use a pipette to absorb the oxalic acid solution in a volume ratio of 1:1 and place it in the conical flask in step 5). The more rare earth oxalate is generated, the more turbid the solution is. Therefore, a portable turbidity meter is used to measure its turbidity. According to the turbidity value and the corresponding relationship between the turbidity value and the ionic phase rare earth content in the sample in Table 1 below, the ionic phase rare earth content of each sample is determined, and records are kept. Samples with a turbidity value less than 5 (i.e., the ionic phase rare earth is less than 100 μg / kg) are quickly separated and sent to step 7) for instrumental analysis;

[0109] Table 1: Turbidity and rare earth content interval division table

[0110]

[0111] 7) All-phase rare earth instrument analysis: Through steps 1) to 6), samples with weak or no mineralization can be quickly diagnosed; rearrange the samples, record the sample numbers, weigh 3 to 5 g of sample from the mineralized sample, control the sample size to 60 to 80 mesh, place it in an X-ray fluorescence analysis plastic cup, and 2 The sample is compacted by the force of the tester, and then the tester is turned on to test the content of all-phase rare earth in the sample. The test time is 15 to 30 seconds. At the same time, elements such as Al, Fe, Ca, and Mg can also be tested. After the test, the content of all-phase rare earth and the content of impurity elements of each sample are sorted out for subsequent analysis and evaluation;

[0112] 8) Elimination of over- and underestimation phenomena: Based on the data analyzed in step 7), the total amount of all-phase rare earth oxides in the sample is calculated according to the following formula (1). When 90% of the total amount of all-phase rare earth oxides in the sample is greater than or equal to 350 μg / kg, and 70% of the total amount of all-phase rare earth oxides in the sample is greater than 350 μg / kg, the sample is retained and sent to the laboratory for analysis. Otherwise, it is only kept as a mineralized sample for further evaluation;

[0113] TREO (3) =(C La +C Ce +C Y )×k3 (1)

[0114] In formula (1), k3 is 1.7 to 2.0; TREO (3)is the total amount of all-phase rare earth oxides fitted by C3 method, in μg / kg; C La , C Ce and C Y They are the contents of the rare earth elements La, Ce and Y in the samples, respectively, and the unit is μg / kg; 9) Laboratory analysis: Through steps 1) to 8), samples that have reached the industrial boundary have been quickly and accurately screened out from a large number of samples. Then, after the samples are naturally dried, they are sent to the laboratory to analyze the ionic phase rare earth (REO) in the samples according to the ionic phase rare earth analysis method (XB / T619-2015). The analysis results obtained are the actual rare earth content in the samples, which can be used for resource estimation.

[0115] Through the implementation of the above process, the mineralized samples were finally screened out in this embodiment, and the results are shown in Table 7. In order to further illustrate the screening function of this method in mineralized samples, in this embodiment, we sent all 51 samples participating in the experiment to the laboratory for analysis.

[0116] Table 7: Wild rare earth content in a rare earth mining area in Yulin City, Guangxi (μg / kg)

[0117]

[0118]

[0119] It can be seen from Table 7 that there are misjudgments in the field rapid analysis, with a misjudgment probability of 7.8%. After adopting the method described in the present invention, all misjudgments are eliminated, and the field rapid analysis results are basically consistent with the laboratory results, and the number and number of discarded samples are consistent with those in the laboratory, which shows that the patented technology has basically reached the analytical reliability of the laboratory.

[0120] Example 3

[0121] Taking a rare earth mine survey project in Cenxi City, Guangxi as an example, the samples are actual samples in the survey project, taken from the Changgangding unit, belonging to the Yanshanian Late Jurassic granite, a set of flesh-red hornblende potassium-containing granite deposits with light rare earth distribution. The thickness of its weathering crust is 5 to 50m, and the samples are taken from the whole weathering layer. The sampling length is 1m. The sampling method is groove sampling, the sample weight is 500g, and the number of samples is 51. After sampling, the samples are quickly analyzed according to the following method, and then the screened samples are sent to the laboratory for analysis. The specific implementation process is as follows:

[0122] 1) Sampling: Collect weathering crust samples with a sample weight of ≥500g, remove weeds and branches for subsequent quick separation;

[0123] 2) Sample dissolution with leaching agent: Use a 1 / 1000 balance to weigh 20 g of the sample in 1), place it in a 100 ml beaker, and use a pipette to absorb 20 ml of a pre-prepared 5% ammonium sulfate solution and mix it with the sample;

[0124] 3) Stirring: Place the beaker in 2) under an electric stirrer at 40 to 120 rpm and stir for more than 1 minute, then remove and centrifuge for precipitation;

[0125] 4) Centrifugal precipitation: Place the beaker in 3) in a 4-position centrifuge, centrifuge at a centrifugal force of 2000-12000g for more than 1 minute, then take it out and let it stand for more than 30 seconds before filtering;

[0126] 5) Filtration: Use medium-speed filter paper to filter the supernatant in the beaker of 4) into a 30ml graduated conical flask. After filtration, the filtrate should be controlled to 10ml and then titrated with oxalic acid;

[0127] 6) Titration: Select a 2% oxalic acid solution prepared in advance, use a pipette to absorb the oxalic acid solution in a volume ratio of 1:1 and place it in the conical flask in step 5). The more rare earth oxalate is generated, the more turbid the solution is. Therefore, a portable turbidity meter is used to measure its turbidity. According to the turbidity value and the corresponding relationship between the turbidity value and the ionic phase rare earth content in the sample in Table 1 below, the ionic phase rare earth content of each sample is determined, and records are kept. Samples with a turbidity value less than 5 (i.e., the ionic phase rare earth is less than 100 μg / kg) are quickly separated and sent to step 7) for instrumental analysis;

[0128] Table 1: Turbidity and rare earth content interval division table

[0129]

[0130] 7) All-phase rare earth instrument analysis: Through steps 1) to 6), samples with weak or no mineralization can be quickly diagnosed; rearrange the samples, record the sample numbers, weigh 5g of sample from the mineralized sample, control the sample size to 40-60 mesh, place it in an X-ray fluorescence analysis plastic cup, and 2 The sample is compacted by the force of the pressure, and then the machine is turned on to test the content of all-phase rare earth in the sample. The test time is 30 seconds. At the same time, elements such as Al, Fe, Ca, and Mg can also be tested. After the test, the content of all-phase rare earth and the content of impurity elements in each sample are sorted out for subsequent analysis and evaluation;

[0131] 8) Elimination of over- and underestimation phenomena: Based on the data analyzed in step 7), the total amount of all-phase rare earth oxides in the sample is calculated according to the following formula (1). When 90% of the total amount of all-phase rare earth oxides in the sample is greater than or equal to 350 μg / kg, and 70% of the total amount of all-phase rare earth oxides in the sample is greater than 350 μg / kg, the sample is retained and sent to the laboratory for analysis. Otherwise, it is only kept as a mineralized sample for further evaluation;

[0132] TREO (3) =(C La +CCe +C Y )×k3 (1)

[0133] In formula (1), k3 is 1.7 to 2.0; TREO (3) is the total amount of all-phase rare earth oxides fitted by C3 method, in μg / kg; C La , C Ce and C Y They are the contents of the rare earth elements La, Ce and Y in the samples, respectively, and the unit is μg / kg; 9) Laboratory analysis: Through 1) to 8), samples that have reached the industrial boundary have been quickly and accurately screened out from a large number of samples. Then, after the samples are naturally dried, they are sent to the laboratory to analyze the ionic phase rare earth (REO) in the samples according to the ionic phase rare earth analysis method (XB / T619-2015). The analysis results obtained are the actual rare earth content in the samples, which can be used for resource estimation.

[0134] Through the implementation of the above process, the mineralized samples were finally screened out in this example, and the results are shown in Table 8. In order to further illustrate the screening function of this method in mineralized samples, in this example, we sent all 50 samples participating in the experiment to the laboratory for analysis.

[0135] Table 8: Wild rare earth content in a rare earth mining area in Cenxi City, Guangxi (μg / kg)

[0136]

[0137]

[0138] It can be seen from Table 8 that there are misjudgments in the field quick classification, and the misjudgment probability is 20%. After adopting the method described in the present invention, all misjudgments are eliminated, and the accuracy rate is increased to 100%. The judgment results are basically consistent with the laboratory results, which shows that the method described in the present invention has basically reached the analytical reliability of the laboratory.

[0139] Through the implementation of the above examples, the field rapid analysis results are basically consistent with the laboratory results, achieving a high degree of consistency between the field rapid analysis technology and the indoor analysis for sample screening; the type of rare earth sample is judged with higher accuracy as the number of detected elements increases. This shows that the method of the present invention has basically achieved the accuracy of the laboratory, and also meets the requirements for rapid field judgment of the rare earth distribution type of the sample.

[0140] The above-described embodiments are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above-described embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, deformation and improvement without departing from the principle of the present invention should be regarded as the protection scope determined by the claims of the present invention.

Claims

1. A method for rapid field screening of ore-bearing weathering crust and evaluation of rare earth ore types, comprising the following steps: Step I, estimating the ionic phase rare earth content in the sample: collecting weathering crust samples, leaching with ammonium sulfate solution and then titrating with oxalic acid solution, observing whether the obtained feed solution has a color reaction, measuring the turbidity of the feed solution with a color reaction, and determining the ionic phase rare earth content of each sample according to the corresponding relationship between the turbidity value and the ionic phase rare earth content in the sample in Table 1 below and making records, discarding samples with a turbidity of less than 5 degrees, and performing full-phase rare earth content analysis on the remaining samples; Table 1: Step II, full-phase rare earth element content analysis: the sample screened in step I is tested for full-phase rare earth element content and impurity element content by X-ray fluorescence spectrometer, and records are kept; wherein, the full-phase rare earth elements are La, Ce and Y, or La, Ce, Pr, Nd and Y; the impurity elements include Al, Fe, Ca, Mg; Step III, eliminate over- and underestimation phenomena: According to the test data of step II, the total amount of all-phase rare earth oxides in the sample is calculated by C3 method or C5 method. When 90% of the total amount of all-phase rare earth oxides in the sample is greater than or equal to 90% of the definition standard of the mine boundary, and 70% of the total amount of all-phase rare earth oxides in the sample is greater than 70% of the definition standard of the mine boundary, the sample is retained and sent to the laboratory for analysis, otherwise it is only kept as a mineralized sample for further evaluation; wherein, When the total rare earth elements detected in step II are La, Ce and Y, the total amount of total rare earth oxides in the sample is calculated using the C3 method. The C3 method calculates the total amount of total rare earth oxides in the sample according to the following formula (1): TREO (3) =(C La +C Ce +C Y )×k3 (1) In formula (1), k3 is 1.7 to 2.0; TREO (3) is the total amount of all-phase rare earth oxides fitted by C3 method, in μg / kg; C La , C Ce and C Y are the contents of rare earth elements La, Ce and Y in the samples, respectively, in μg / kg; When the total rare earth elements detected in step II are La, Ce, Pr, Nd and Y, the total amount of total rare earth oxides in the sample is calculated using the C5 method. The C5 method calculates the total amount of total rare earth oxides in the sample according to the following formula (2): TREO (5) =(C La +C Ce +C Pr +C Nd +C Y )×k5 (2) In formula (2), k5 is 1.2 to 1.4; TREO (5) is the total amount of all-phase rare earth oxides fitted by the C5 method, in μg / kg; C La , C Ce , C Pr , C Nd and C Y are the contents of rare earth elements La, Ce, Pr, Nd and Y in the samples, respectively, in μg / kg; Step IV: Send the sample screened out in step III to the laboratory to analyze the ionic phase rare earth content therein according to the ionic phase rare earth analysis method. The obtained analysis result is the true ionic phase rare earth content in the sample, and the analysis result is used for resource estimation; Step V: Based on the detection data of step II, the type of rare earth ore is evaluated using the following formula (3) or formula (4); wherein: When the full-phase rare earth elements detected in step II are La, Ce and Y, if the following formula (3) is satisfied, the sample is determined to be a heavy rare earth type, otherwise the sample is a light rare earth type; 1.5×(C La +C Ce )>C Y (3) In formula (3), C La , C Ce and C Y are the contents of rare earth elements La, Ce and Y in the samples, respectively, in μg / kg; When the full-phase rare earth elements detected in step II are La, Ce, Pr, Nd and Y, if the following formula (4) is satisfied, the sample is determined to be a medium-heavy rare earth type, otherwise the sample is a light rare earth type; (C La +C Ce +C Pr +C Nd +) / C Y ≤2 (4) In formula (4), C La , C Ce , C Pr , C Nd and C Y They are the contents of rare earth elements La, Ce, Pr, Nd and Y in the samples respectively, and the unit is μg / kg.

2. The method according to claim 1, characterized in that: Step I specifically includes the following steps: 1) Sampling: Collect weathering crust samples, remove weeds and branches, and set aside; 2) Sample dissolution with leaching agent: Accurately weigh a certain amount of sample and place it in a container, add ammonium sulfate solution and mix with the sample, stir to dissolve, then centrifuge and filter, and collect the filtrate; 3) Titration: add oxalic acid solution to the filtrate, observe the color change of the feed solution after shaking, measure the turbidity of the feed solution with color reaction, and determine the ionic phase rare earth content of each sample according to the corresponding relationship between turbidity and ionic phase rare earth content in the sample in Table 1 and keep a record, discard the samples with turbidity less than 5 degrees, and analyze the whole phase rare earth content of the remaining samples.

3. The method according to claim 1 or 2, characterized in that: The concentration of the ammonium sulfate solution is 3 to 5 w / w%.

4. The method according to claim 1 or 2, characterized in that: The concentration of the oxalic acid solution is 2 to 3 w / w%.

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