Method for determining total moisture in carnallite, carnallite-containing rock salt or mirabilite mineral

Abstract

The invention relates to the technical field of rock and ore testing, in particular to a method for measuring total moisture in carnallite, carnallite-containing rock salt or mirabilite minerals. The determination method specifically comprises the following steps: weighing an air-dried sample, putting the air-dried sample into a weighing container, drying at 175-185 DEG C for 3-5 hours, slightly cooling, putting the sample into a dryer, cooling to room temperature, and weighing; repeatedly drying for 30 minutes and then weighing until the weight is constant; calculating the total moisture content according to a formula provided by the invention; in the formula, omega (H2O-) is the mass fraction of the total moisture; m1 is the mass of the empty weighing container; m2 is the mass of the dried weighing container and the sample; m is the mass of the weighed sample. The invention determines the temperature when the carnallite completely loses adsorbed water, crystal water becomes anhydrous carnallite (KCl.MgCl2) and is not decomposed, and establishes a method for determining the total moisture in carnallite, carnallite-containing rock salt or mirabilite minerals.

Description

Technical Field

[0001] The present application relates to the technical field of rock and mineral testing, and in particular to a method for determining the total moisture in carnallite, rock salt containing carnallite or mirabilite minerals. Background Art

[0002] For the testing of various types of rock salt or thenardite minerals, the test methods should generally be selected according to the rock salt and thenardite minerals. Among them, the main determination of moisture is adsorbed water and total water. The relevant methods refer to "Rock and Ore Analysis Procedure Salt Ore Analysis Procedure IV Rock and Thenardite Ore Analysis DZG 93-08" (I) Gravimetric determination of adsorbed water and (II) Gravimetric determination of total water. However, rock salt or thenardite minerals are generally accompanied by a large number of other minerals. When rock salt or thenardite minerals are accompanied by carnallite or when carnallite is the main mineral, the method for determining adsorbed water and total water is no longer applicable. The reasons for inapplicability are as follows:

[0003] (1) The adsorbed water is measured by the drying loss method at 105°C. The scope of application of this method clearly states that it is suitable for the determination of adsorbed water in relatively pure rock salt.

[0004] The main components of carnallite are KCl·MgCl 2 6H 2 O, starts to lose water at around 100°C, and completely dehydrates with a small amount of hydrolysis when heated to 176°C. Therefore, constant weight cannot be achieved when measured at 105°C, so the adsorbed water in the sample cannot be obtained when rock salt or mirabilite minerals are associated with carnallite or when carnallite is the main mineral.

[0005] (2) Total moisture content is determined by ignition gravimetric method at 550°C. The method notes clearly state that "this method is not suitable for samples with high organic content, or for the analysis of samples containing carnallite, bischofite or other calcium-magnesium chlorides."

[0006] When carnallites are heated to 176°C, they are completely dehydrated and accompanied by a small amount of hydrolysis. Since hydrolysis gradually occurs with increasing temperature, it is impossible to obtain the true value of the total water content in the sample when rock salt or mirabilite minerals accompany carnallites or when carnallites are the main mineral.

[0007] Based on the above, the detection methods in the current related technologies cannot accurately measure the water content in samples when rock salt or mirabilite minerals are associated with carnallite or when carnallite is the main mineral. However, the water content is one of the important indicators for evaluating carnallite, rock salt containing carnallite or mirabilite minerals, and the adsorbed water and crystal water in carnallite cannot be strictly tested in sections, so the total water content cannot be measured.

[0008] Therefore, it is necessary to find a suitable determination method to determine the total moisture content of samples when rock salt or mirabilite minerals are associated with carnallite or when carnallite is the main mineral. Summary of the invention

[0009] The present application provides a method for determining the total moisture in carnallites, rock salt containing carnallites or mirabilite minerals.

[0010] The present invention analyzes the water loss temperature of carnallites during heating process and determines that carnallites completely lose adsorbed water and crystal water to become anhydrous carnallites (KCl·MgCl 2 ) and the temperature when decomposition is not carried out, the determination of the total moisture in carnallites, rock salt containing carnallites or thenardite minerals is solved, and a method for determining the total moisture in carnallites, rock salt containing carnallites or thenardite minerals is established.

[0011] The present application provides a method for determining the total moisture in carnallites, rock salt containing carnallites or mirabilite minerals, using the following technical scheme:

[0012] A method for determining the total moisture in carnallites, rock salt containing carnallites or mirabilite minerals, the determination method specifically comprising:

[0013] Weigh the air-dried sample and place it in a weighing container. Dry it at 175-185℃ for 3-5h. After it cools down slightly, place it in a desiccator, cool it to room temperature, and weigh it. Repeat the drying for 30min and weigh it again until constant weight is reached.

[0014] Calculate the total moisture content as follows:

[0015] ω(H 2 O - )=(m 1 +mm 2 ) / m×100%;

[0016] Where: ω(H 2 O - ) is the mass fraction of total water, %; m 1 is the mass of the empty weighing container, g; m 2 is the mass of the weighing container and sample after drying, g; m is the mass of the weighed sample, g.

[0017] Optionally, the total moisture content in the sample is in the range of ≥0.1%.

[0018] In summary, the present application includes at least one of the following beneficial technical effects:

[0019] The present invention analyzes the water loss temperature of carnallites during heating process and determines that carnallites completely lose adsorbed water and crystal water to become anhydrous carnallites (KCl·MgCl 2) and the temperature when decomposition is not carried out, the determination of the total moisture in carnallites, rock salt containing carnallites or thenardite minerals is solved, and a method for determining the total moisture in carnallites, rock salt containing carnallites or thenardite minerals is established.

[0020] Since there is no standard method for the moisture (adsorbed water, total moisture) in carnallites, rock salt containing carnallites or mirabilite minerals, it is difficult to measure. In this paper, based on the characteristics of carnallites, the measurement temperature of total moisture is controlled at 180°C, and the total moisture result is obtained stably with a detection limit of 0.1%. The precision meets the requirements of "DZ / T 0130-2006 Quality Management Standards for Laboratory Testing of Geology and Mineral Resources", and the accuracy is added in accordance with "DZ / T 0130.3-2006 Quality Management Standards for Laboratory Testing of Geology and Mineral Resources Part 3: Chemical Composition Analysis of Rock and Mineral Samples" 4.3.3.4 and the second level control (control range is 99.0-101.0%) for quality control, which meets its requirements. DETAILED DESCRIPTION

[0021] Before describing the embodiments of the present application in detail, it should be understood that the terms used herein are only used for the purpose of describing specific embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by ordinary technicians in the field to which the terms belong.

[0022] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of this application, unless otherwise specified, the meaning of "plurality" is two or more.

[0023] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0024] In the present application, the terms "comprise" or "include" are open expressions, that is, including the contents specified in the present application but not excluding other contents.

[0025] The present application provides a method for determining the total moisture in carnallites, rock salt containing carnallites or mirabilite minerals.

[0026] (I) Scope of application

[0027] The above method is applicable to the determination of total water content in carnallite, rock salt containing carnallite or mirabilite minerals. The determination range is ≥ 0.1%.

[0028] (II) Principle

[0029] The mass lost by carnallite, rock salt containing carnallite or Glauber's salt mineral after being dried at 180°C to constant weight is the total moisture content.

[0030] Carnallite starts to lose water at around 100°C, and when heated to 176°C, it will be completely dehydrated with a small amount of hydrolysis. Therefore, the temperature of the heating dehydration process can be controlled at around 180°C, so that the adsorbed water and crystal water in carnallite, carnallite-containing rock salt or mirabilite minerals are completely lost, and anhydrous carnallite (KCl·MgCl 2 ), at this time, the hydrolysis rate of carnallite is low and the effect on the determination of its total moisture content is negligible.

[0031] (III) Sample

[0032] According to "DZ / T 0130.2-2006 Quality Management Standards for Laboratory Testing of Geology and Mineral Resources Part 2: Preparation of Rock and Mineral Analysis Samples" 6.4, rock salt, sodium sulfate, and gypsum analysis samples (40-50℃) are dried.

[0033] (IV) Analysis steps

[0034] Weigh 1.0000g of air-dried sample with a particle size of 0.149mm (100 mesh), place it in a weighing bottle (35mm in diameter) that has been dried at 180℃ and weighed to constant weight, shake it gently to spread the sample evenly on the bottom, half-open the bottle cap, put it in an oven, and dry it at 180℃ for 4h. Take it out, cover the bottle cap tightly, put it in a desiccator after it cools slightly, cool it to room temperature, weigh it (accurate to 0.0001g, slightly open the bottle cap before weighing to balance the pressure in the bottle with the atmospheric pressure), repeat drying for 30min and weighing again until constant weight is reached.

[0035] The total water content is calculated as follows: ω(H 2 O - )=(m 1 +mm 2 ) / m×100%

[0036] Where: ω(H 2 O - ) is the mass fraction of total water, %; m 1 is the mass of the empty weighing bottle, g; m 2 is the mass of the weighing bottle and sample after drying, g; m is the mass of the weighed sample, g.

[0037] The determination method provided in the present application solves the problem of determining the total moisture in carnallite, rock salt containing carnallite or mirabilite minerals, which are difficult to be stabilized in the adsorption moisture test at 105°C, and the material decomposition occurs at 550°C while the total moisture is lost. In the present application, the determination of the total moisture at 180°C will remain stable.

[0038] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. The embodiments described below are exemplary and are only used to explain the present application, and cannot be interpreted as limiting the present application.

[0039] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0040] The present application is further described in detail below in conjunction with the embodiments and test results.

[0041] The determination method provided in this application is used to carry out method tests and determination of actual samples, including detection limit, precision, accuracy and actual sample determination results.

[0042] Example

[0043] Example 1

[0044] This embodiment provides a method for determining the total moisture in carnallite, rock salt containing carnallite, or mirabilite minerals. The method detection limit is determined in accordance with the provisions of the "HJ 168-2020 Technical Guidelines for the Development of Environmental Monitoring Analysis Method Standards". The details are as follows:

[0045] According to all the steps of sample analysis, the blank test was repeated 7 times, each measurement result was converted into the concentration or content in the sample, the standard deviation of 7 parallel measurements was calculated, and the method detection limit was calculated according to the following formula: MDL = t (n-1, 0.99) × S. Where: MDL - method detection limit; n - number of parallel measurements of the sample; t - distribution (one-sided) when the degree of freedom is n-1 and the confidence level is 99%; S - standard deviation of n parallel measurements.

[0046] Among them, when n is 7 times, the confidence level is 99%, t(n-1,0.99)=3.143. The detection limit of the sample is 4 times as the lower limit of determination, that is, RQL=4×MDL. The calculation results of the detection limit and the lower limit of determination of this method are shown in Table 1.

[0047] As can be seen from Table 1, after verification, the detection limit of total moisture in the determination method provided by this application is 0.1%.

[0048] Table 1 Detection Limit of Total Moisture

[0049]

[0050]

[0051] Example 2

[0052] This example provides a method for determining the total moisture in carnallite, rock salt containing carnallite or mirabilite minerals. According to the requirements of this method, 6 parallel determinations were carried out on actual samples to determine the method precision. The determination results are shown in Table 2 specifically.

[0053] Table 2 Precision Determination

[0054]

[0055] As can be seen from Table 2, after verification, for 6 parallel determinations of actual samples (2302054, 2302090), the allowable limits of relative deviation Yc (%) between the maximum and minimum determination values are 1.55% and 2.20% respectively, and the absolute values of relative deviation RD (%) between the maximum and minimum determination values are 0.59% and 0.57% respectively. RD% < Yc%, which meets the requirements of the "Quality Management Specification for Geological and Mineral Laboratory Testing DZ / T 0130 - 2006", and the precision verification is qualified.

[0056] Example 3

[0057] This example provides a method for determining the total moisture in carnallite, rock salt containing carnallite or mirabilite minerals. In this example, the method accuracy was determined.

[0058] Since there are no standard substances for carnallite, etc., it is impossible to trace the accuracy using standard substances. Now, personnel comparison and the sum of the contents of each element in carnallite are used for accuracy control. The sum is carried out according to the second-level control of the sum in "Quality Management Specification for Geological and Mineral Laboratory Testing Part 3: Chemical Composition Analysis of Rock and Mineral Samples DZ / T 0130.3 - 2006", and the control range is 99.0 - 101.0%. The accuracy control is shown in Table 3.

[0059] Table 3 Accuracy Determination

[0060]

[0061] Example 4

[0062] This embodiment provides a method for determining the total water content in carnallites, rock salt containing carnallites, or mirabilite minerals.

[0063] In this embodiment, 124 actual samples were analyzed, 49 samples were randomly inspected, and various comparison tests were performed, with a sampling ratio of 40%.

[0064] (1) Comparison test results at 105℃ and 180℃

[0065] 105℃ parallel comparison test: 49 items were randomly inspected, of which 28 were qualified, 21 were unqualified, and the constant weight was unstable, with a qualified rate of 58.3%.

[0066] 180℃ parallel comparison test: 49 items were randomly inspected, of which all 49 items were qualified, the constant weight was normal and stable, and the qualified rate was 100%.

[0067] The test results of 180℃ and 105℃ are different: 124 pieces were checked, 5 were basically parallel, and the difference of the remaining 119 pieces was 0.15~31.01%, and 180℃ was greater than 105℃.

[0068] The detailed values ​​are shown in Table 4.

[0069] Table 4 Results of parallel comparison tests at 105℃ and 180℃

[0070]

[0071]

[0072]

[0073]

[0074] (2) Comparison test results of 105℃ and 180℃ summation accuracy

[0075] 124 actual samples were analyzed and the accuracy comparison was performed at 105℃ and 180℃. The summation was carried out in accordance with 4.3.3.4 and the second level control of "DZ / T0130.3-2006 Quality Management Standards for Laboratory Testing of Geology and Mineral Resources Part 3: Chemical Composition Analysis of Rock and Mineral Samples" with a control range of 99.0-101.0%.

[0076] 105℃ Accuracy sum: 124 samples were tested, of which 27 were qualified and 97 were unqualified, with a qualified rate of 21.8%.

[0077] 180℃ Accuracy sum: 124 samples were tested, all 124 samples were qualified, with a qualified rate of 100%.

[0078] The detailed values ​​are shown in Table 5.

[0079] Table 5 Comparison test results of 105℃ and 180℃ summation accuracy

[0080]

[0081]

[0082]

[0083]

[0084]

[0085] Since there is no standard method for the moisture (adsorbed water, total moisture) in carnallites, rock salt containing carnallites or mirabilite minerals, it is difficult to measure. In this paper, based on the characteristics of carnallites, the measurement temperature of total moisture is controlled at 180°C, and the total moisture result is obtained stably with a detection limit of 0.1%. The precision meets the requirements of "DZ / T 0130-2006 Quality Management Standards for Laboratory Testing of Geology and Mineral Resources", and the accuracy is added in accordance with "DZ / T 0130.3-2006 Quality Management Standards for Laboratory Testing of Geology and Mineral Resources Part 3: Chemical Composition Analysis of Rock and Mineral Samples" 4.3.3.4 and the second level control (control range is 99.0-101.0%) for quality control, which meets its requirements.

[0086] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for determining the total moisture in carnallites, rock salt containing carnallites or mirabilite minerals, characterized in that: The determination method is specifically: Weigh the air-dried sample and place it in a weighing container. Dry it at 175-185℃ for 3-5h. After it cools down slightly, place it in a desiccator, cool it to room temperature, and weigh it. Repeat the drying for 30min and weigh it again until constant weight is reached. Calculate the total moisture content according to the following formula: ω(H2O - )=(m1+m-m2) / m×100%; Where: ω(H2O - ) is the mass fraction of total moisture, %; m1 is the mass of the empty weighing container, g; m2 is the mass of the weighing container and the sample after drying, g; m is the mass of the sample weighed, g.

2. The measuring method according to claim 1, characterized in that The total moisture content of the sample is in the range of ≥0.1%.

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