Microcalorimetric method for accurately measuring surface water wettability of ore grains

Abstract

The invention discloses a microcalorimetric method for accurately measuring the surface water wettability of mineral particles, and belongs to the technical field of mineral separation. According to the method, a second order line between the mineral reaction heat and the contact angle is established for the first time, the following formula is obtained, in the formula, Q is the reaction heat, theta is the contact angle, and by means of the formula, when the surface water wettability of the mineral is measured, only the reaction heat needs to be measured, and the surface water wettability of the mineral can be measured. And substituting the reaction heat into a second-order linear quantitative equation to obtain the ore grain surface contact angle, namely the surface water wettability. The established second-order linear quantitative model between the reaction heat and the contact angle is accurate and reliable, the test process is simple and easy to operate, and the method has the advantages of being high in universality, efficient, accurate and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to a microcalorimetric method for accurately measuring the water wettability of a mineral particle surface, and belongs to the technical field of mineral processing. BACKGROUND

[0002] Minerals are an important resource essential for national economic production and social development. As the premise of being used as a basic raw material in various industries, minerals need to be separated and enriched through processes such as crushing, grinding, gravity separation, and flotation. Fine-grained mineral recovery often uses flotation technology. In the flotation process, the wettability of the mineral particle surface is crucial to the separation and enrichment effect. If the mineral particle surface contains more hydrophilic groups such as oxygen-containing groups, the surface hydrophilicity is strong, and the adsorption of water droplets on the surface is high, i.e., the water wettability is strong, which is not conducive to the efficient mineralization of mineral particles and bubbles, resulting in poor flotation effect. Conversely, if the mineral particle surface contains more hydrophobic groups, the surface hydrophobicity is strong, the water wettability is poor, and the flotation effect is good. Therefore, accurately and efficiently characterizing and evaluating the water wettability of the mineral particle surface is of great significance and value for efficient flotation separation and recovery of the mineral particle surface.

[0003] Currently, methods commonly used to measure the water wettability of a mineral particle surface include the sessile drop method, bubble capture method, and capillary penetration method. However, each method has certain limitations. For example, the sessile drop method and bubble capture method require the use of blocky ore samples or the pressing of mineral particles into a sheet. The former cannot accurately evaluate the in-situ wettability of the surface of a particulate mineral because there are certain differences between the surfaces of blocky and particulate ore samples, and particulate ore samples are commonly used in the flotation process. The pressing problem is that not all mineral particles have good adhesion, and mineral particles with poor adhesion cannot be effectively pressed into a sheet, which will prevent subsequent contact angle measurement and evaluation of the wettability of the mineral particles. This method has the problem of poor adaptability of mineral particles. The capillary penetration method has the problems of long test time, poor repeatability, and low accuracy when characterizing the water wettability of the mineral particle surface. In summary, the existing methods for measuring the water wettability of a mineral particle surface have the problems of distorted results, narrow range of application of mineral particles, low efficiency, and poor accuracy. In view of the above limitations and the changes in the interfacial surface and free energy in wetting, It is necessary to propose a method for accurately and efficiently measuring the water wettability of a mineral particle surface from the perspective of thermodynamics. SUMMARY

[0004] In order to overcome the problems in the prior art, the purpose of the present application is to provide a microcalorimetric method for accurately measuring the water wettability of a mineral particle surface, which can be used to efficiently and accurately characterize the in-situ water wettability of the surface of different types of mineral particles, thereby solving the problems of distorted results, low efficiency, poor accuracy, and poor adaptability in the existing methods for measuring the water wettability of a mineral particle surface.

[0005] In order to achieve the above object, the present application is realized by the following technical scheme: A microcalorimetric method for accurately measuring water wettability of mineral particle surface, comprising the following steps: The reaction heat curve of the mineral particle is measured, and the area of the reaction heat curve is calculated as the reaction heat, which is substituted into the formula as shown in formula I to calculate the contact angle, and the water wettability of the mineral particle can be judged through the contact angle; I In the formula, Q is the reaction heat, and θ is the contact angle.

[0006] Preferably, the reaction heat curve is determined by isothermal microcalorimetry, and distilled water is used in the determination process.

[0007] Preferably, the mineral particle is a metal mineral, an energy mineral or a non-metallic mineral.

[0008] Preferably, the metal mineral is smithsonite, marmatite, chalcopyrite, pyrite, galena, molybdenite, scheelite, blue copper ore and malachite.

[0009] Preferably, the energy mineral is lignite, anthracite, long flame coal and coking coal.

[0010] Preferably, the non-metallic mineral is quartz, apatite and dolomite.

[0011] The present application has the following beneficial effects: (1) The microcalorimetric method for measuring the water wettability of the mineral particle surface is simple and convenient, the second-order linear model between the reaction heat and the contact angle has high fitting precision, and the efficient and accurate characterization of the water wettability of the mineral particle surface is truly realized.

[0012] (2) The microcalorimetric method for measuring the water wettability of the mineral particle surface has strong universality, and can be widely used for the characterization of the water wettability of the surface of various mineral particles, avoiding the problem that the test methods are not unified due to the differences in the physical and chemical properties of the surfaces of different types of minerals.

[0013] (3) In the present application, the mineral to be measured and the mineral used for flotation have the same particle size, and the mineral particle does not need to be crushed and ground or pressed before testing, avoiding the influence of the particle size and the surface physical inhomogeneity of the mineral on the water wettability, solving the problem that the test results of the sessile drop method do not match the water wettability of the flotation mineral, and truly realizing the in-situ characterization of the water wettability of the surface of the flotation mineral particle. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 The contact angle (a) of quartz and water droplets and the reaction heat curve (b) in Example 1.

[0015] Figure 2Contact angle (a) and reaction heat curve (b) of sphalerite with water droplet in Example 1.

[0016] Figure 3 Contact angle (a) and reaction heat curve (b) of apatite with water droplet in Example 1.

[0017] Figure 4 Contact angle (a) and reaction heat curve (b) of lignite with water droplet in Example 1.

[0018] Figure 5 Contact angle (a) and reaction heat curve (b) of sphalerite with water droplet in Example 1.

[0019] Figure 6 Contact angle (a) and reaction heat curve (b) of pyrite with water droplet in Example 1.

[0020] Figure 7 Contact angle (a) and reaction heat curve (b) of galena with water droplet in Example 1.

[0021] Figure 8 Contact angle (a) and reaction heat curve (b) of chalcopyrite with water droplet in Example 1.

[0022] Figure 9 Contact angle (a) and reaction heat curve (b) of molybdenite with water droplet in Example 1.

[0023] Figure 10 Contact angle (a) and reaction heat curve (b) of anthracite with water droplet in Example 1.

[0024] Figure 11 A fitting schematic diagram between the reaction heat of the mineral particle and the surface contact angle thereof measured based on the thermodynamic theory of the present application. DETAILED DESCRIPTION

[0025] The technical solutions provided by the present application will be described in detail below in combination with the embodiments, but they should not be understood as limiting the scope of protection of the present application.

[0026] The chemical reagents not described in the specific embodiments of the present application are all commercially available analytical pure reagents for experiments.

[0027] The equipment used for reaction heat test in the examples is Calvet Cryo C80 type calorimeter.

[0028] Example 1 The formula derivation process of a microcalorimetric method for accurately measuring the water wettability of the surface of a mineral particle is as follows: (1) Selecting smithsonite, sphalerite, chalcopyrite, pyrite, galena and molybdenite as representative minerals of non-ferrous metals, lignite and anthracite as representative minerals of energy, quartz and apatite as representative minerals of non-metals, a total of 10 kinds of minerals, each of the above minerals is crushed and ground to 200 mesh (74 μm) or less, and each of the mineral particles is divided into two parts for standby.

[0029] (2) Take a part of the mineral particles obtained in step (1), and press the mineral particles into circular sheet-shaped objects by means of a tablet press, and boric acid is added during the tablet pressing process to increase the compactness of the circular sheet-shaped objects, the mass ratio of boric acid to mineral particles is about 1:4, and finally the contact angle θ of distilled water on the surface of each sheet-shaped object is measured by means of an SDC-350KS type contact angle measuring instrument (manufacturer: Shengding Precision Instrument Co., Ltd. in Dongguan), and the measurement results are shown in Figure 1 (a) of -10 (a).

[0030] (3) The remaining mineral particles in step (1) are placed in a vacuum drying oven for drying to remove free water contained on the surface and inside of the mineral particles.

[0031] (4) Weigh 0.1 g of the dried mineral particles in step (3) and 1 mL of distilled water, and add the mineral particles and distilled water into the lower and upper reaction tanks of a microcalorimeter, respectively, and isolate the middle part of the upper and lower reaction tanks with a polytetrafluoroethylene film, and then helium gas is introduced into the reaction chamber, and when the heat flow is stable, the polytetrafluoroethylene film between the upper and lower reaction tanks is pierced to allow the distilled water to wet the mineral particles under the action of gravity, and then the heat flow-time curve (i.e. reaction heat curve) of the process of the mineral particle surface being wetted by water is collected, and in this embodiment, the equipment used to represent the heat change (i.e. reaction heat) when the water droplets wet the surface of the mineral particles is a Calvet Cryo C80 type calorimeter, and the single test time is about 35 min.

[0032] (5) After the microcalorimeter test is completed, the heat flow-time curve of the wetting of the surface of each mineral particle by distilled water can be obtained, as shown in Figure 1 (b) of -10 (b), and the heat flow-time curve of each mineral particle is integrated by means of the analysis software of the microcalorimeter to calculate the peak area of the curve, so as to obtain the reaction heat of each mineral particle after being wetted by distilled water, as shown by the reaction heat marked in Figure 1 (b) of -10 (b).

[0033] (6) By means of a drawing analysis software Origin 2024, the reaction heat value Q and the contact angle value θ of the mineral particles after being wetted by distilled water are respectively subjected to first-order and second-order linear quantitative fitting, and based on the principles of maximum fitting degree and minimum root mean square error, the relationship between Q and θ is analyzed and obtained as follows: , the fitting degree is 0.9997, and the root mean square error is 0.0209, as shown in Figure 11As shown, it is indicated that the second order linear quantitative model is consistent between the reaction heat Q of the mineral particle and the contact angle θ.

[0034] Example 2 A microcalorimetric method for accurately measuring the water wettability of the surface of a mineral particle is as follows: The non-ferrous metal minerals of scheelite, blue copper ore, malachite and red copper ore, the energy minerals of long-flame coal and coking coal, and the non-metallic mineral of dolomite are selected, the above minerals are ground to 200 mesh (74 μm) or less and are pre-dried and dehydrated, then 0.1 g of the mineral particles and 1 mL of distilled water are weighed and added to the lower and upper reaction tanks of the microcalorimeter, respectively, the reaction heat between the mineral particles and the distilled water is characterized under the test procedure defined in the present application, the measurement time is about 35 min, the heat flow-time curve area of each mineral particle is calculated to obtain the reaction heat Q between each mineral particle and the distilled water, and the reaction heat Q is substituted into the second order linear equation established in Example 1 to obtain the water wettability of the surface of the mineral particle, and the results are shown in Table 1.

[0035] Table 1 In order to further verify the accuracy of the method described in the present application, the contact angle of the mineral particles (the non-ferrous metal minerals of scheelite, blue copper ore, malachite and red copper ore, the energy minerals of long-flame coal and coking coal, and the non-metallic mineral of dolomite) is measured by the sessile drop method, and the results are shown in Table 1. As can be seen from Table 1, it is feasible to measure the contact angle by the method described in the present application.

Claims

1. A microcalorimetric method for accurate measurement of the water wettability of mineral grain surfaces, characterized by: It comprises the following steps: The reaction heat curve of the ore grain is measured, and the area of the reaction heat curve is calculated as the reaction heat, which is substituted into the formula as shown in Formula I to calculate the contact angle, and the water wettability of the ore grain is determined through the contact angle. Ⅰ； In the formula, Q is the reaction heat, and θ is the contact angle.

2. The microcalorimetric method for accurate measurement of the wettability of the surface of a mineral grain according to claim 1, characterized in that: The reaction heat curve is determined by isothermal microcalorimetry, and distilled water is used in the determination process.

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