Calculation method for peroxidation defect concentration of earth mineral

Abstract

The invention belongs to the technical field of earth mineral analysis, and particularly relates to a calculation method of earth mineral peroxide defect concentration. The method comprises the following steps: firstly, obtaining the concentration of each macroelement ion in a mineral, then, respectively calculating the total concentration of tetrahedral net-making cations and the concentration of O2 <-> according to the obtained concentration of each macroelement ion, then, calculating the non-bridge oxygen index of the mineral according to the total concentration of tetrahedral net-making cations and the concentration of O2 <->, and finally, calculating the non-bridge oxygen index of the mineral according to the total concentration of tetrahedral net-making cations and the concentration of O2 <->. And inversely calculating the concentration of the peroxidation defect according to the non-bridge oxygen index. According to the method, firstly, the concentration of each ion in the mineral is actually measured, then the non-bridge oxygen index of the mineral is calculated, and then the mineral peroxidation defect concentration is quantitatively and inversely calculated according to the non-bridge oxygen index, so that quantitative analysis on the peroxidation defect in the mineral can be realized, and a brand new method is provided for quantitative research on the peroxidation defect in the earth mineral.

Description

Technical Field

[0001] The invention belongs to the technical field of earth mineral analysis, and in particular relates to a method for calculating the peroxygen defect concentration of earth minerals. Background Art

[0002] Minerals are the basic components of silicate rocks, composed of tetrahedral structures, which are connected by shared oxygen ion corners to form a three-dimensional network, forming [ SiO 4 ] 4- or[ AlO 4 ] 5- The tetrahedral structure can exist independently to form an island tetrahedral structure, or it can exist by sharing corner oxygen to form other tetrahedral structures such as chains. The anions on the tetrahedral coordination structure are O 2- , and cations are divided into network-building ions (mainly Si 4+ and Al 3+ ) and variable network ions (mainly Mg 2+ , K + , Ca 2+ The network-forming ions constitute the basic tetrahedral structure, and the variable network ions play the role of balancing the electric charge, making the mineral as a whole electrically neutral.

[0003] The non-bridging oxygen index describes the number of cations coordinated per tetrahedron. O 2- When the mineral does not contain defects, in the framework silicon-oxygen tetrahedral structure, the oxygen ions connected to the coordinated cations of each tetrahedral structure are connected to other tetrahedrons and are all bridging oxygen, so the non-bridging oxygen index is 0. Similarly, for island and chain tetrahedral structures, the non-bridging oxygen index should be 4 and 2. When mineral rocks are formed in nature, their melts will be doped during the cooling and crystallization process. O - The structure forms an oxygen defect. An oxygen defect is a kind of inherent defect in mineral rocks, which consists of two O - It is often in a dormant state and is force-sensitive. Under stress, the peroxygen defect will break. O - Will form freely mobile ions, freely mobile O - Will capture nearby O 2- The electrons in O - Convert to O2- , and loses an electron O 2- will lose an electron and become O - .therefore O - The position shift occurs, and under the action of oxidation, O - It will migrate to the surface along the crust and in the direction of maximum stress gradient. During the migration process, it will generate low-frequency electromagnetic radiation. When accumulated on the surface, it will penetrate the air and form surface electric field anomalies and other abnormal earthquake precursor phenomena.

[0004] The process of forming peroxygen defects in mineral rocks is as follows: First, during the cooling process of the mineral melt, the tetrahedral structure will form a hydroxyl structure under the action of melt water doping ( OH - ): ≡X•+OH - =≡X-OH ,in, X The logo indicates the network-building cation; then, the hydroxyl structure is not stable in the melt structure and is prone to forming an oxygen free radical structure ( O• ) and hydrogen radicals ( •H ),Right now ≡ X-OH→≡X-O•+•H ; Then, two oxygen radical structures combine to form a peroxy defect: ≡X-O•+•O-X≡=≡X-O- O-X≡ , and two hydrogen radicals form hydrogen gas: H•+•H=H 2 . Peroxidation defects in O - Replaced the silicon-oxygen tetrahedron O 2- The position of the mineral changes the non-bridging oxygen index of the whole mineral. However, in the current research on mineral peroxygen defects, qualitative research is often used in the interpretation of earthquake precursor anomalies, and there is still a lack of quantitative research on the concentration of peroxygen defects. Summary of the invention

[0006] The present invention provides a method for calculating the concentration of peroxygen defects in earth minerals. The method is based on the fact that minerals are doped during their formation. O - The structure will then change the principle of the non-bridging oxygen index of the mineral. First, the concentration of each ion in the mineral is measured, and then the non-bridging oxygen index of the mineral is calculated. Finally, the mineral peroxygen defect concentration is quantitatively calculated based on the non-bridging oxygen index.

[0007] The method comprises the following steps: S1, obtaining the concentration of each constant element ion in the mineral, wherein the constant element ions include: Na + , K+ , Mg 2+ , Ca 2+ , Mn 2+ , Fe 2+ , Fe 3+ , Al 3+ , Ti 4+ , P 5+ , Si 4+ and O 2- ; S2, according to the concentration of each constant element ion obtained, the total concentration of tetrahedral network cations and O 2- Concentration, get O 2- The concentration is ∑ M 2- , the total concentration of tetrahedral network-building cations is ∑ M 4+ , where ∑ M 4+ express Si 4+ and∑ M 3+ The concentration of the sum of M 3+ express Fe 3+ and Al 3+ The total concentration, or M 3+ represents the total positive charge of each valence state network-changing cation; in step S2, the total concentration of each valence state network-changing cation is also calculated as ∑ M + ,∑ M 2+ and∑ Ti 4+ , where ∑ M + express Na + , K + and P 5+ The total concentration, ∑ M 2+ express Mg 2+ , Ca 2+ , Mn2+ and Fe 2+ The total concentration, ∑ Ti 4+ express Ti 4+ The total concentration of M + +2∑ M 2+ +4∑ Ti 4+ That is, the total positive charge of each valence state variable cation; Fe 3+ and Al 3+ The total concentration of each valence state of the cations is related to the total number of positive charges ∑ M + +2∑ M 2+ +4∑ Ti 4+ The relationship between: If Fe 3+ and Al 3+ Total concentration of M + +2∑ M 2+ +4∑ Ti 4+ , then take ∑ M + +2∑ M 2+ +4∑ Ti 4+ =∑ M 3+ , that is, M 3+ =∑ M + +2∑ M 2+ +4∑ Ti 4+ Otherwise, if Fe 3+ and Al 3+ Total concentration ≤∑ M + +2∑ M 2+ +4∑ Ti 4+ , then ∑ M 3+ Pick Fe 3+ and Al 3+ Total concentration; S3, according to the total concentration of tetrahedral network cations andO 2- The concentration of the mineral is calculated using the non-bridging oxygen index; S4, the concentration of the peroxygen defects is calculated based on the non-bridging oxygen index.

[0008] In a specific embodiment, in step S1, the specific steps of obtaining the concentration of each constant element ion in the mineral are: first obtaining the concentration of each oxide in the mineral, and then calculating the concentration of each constant element ion according to the chemical molecular formula of each oxide.

[0009] In a specific embodiment, in step S1, an inductively coupled plasma emission spectrometer or a whole rock analyzer is used to obtain the concentration of each oxide in the mineral.

[0010] In a specific embodiment, in step S3, according to O 2- Concentration M 2- and the total concentration of tetrahedral network-building cations∑ M 4+ , calculate the non-bridging oxygen index of the mineral NBO / T for: NBO / T =(2∑ M 2- -4∑ M 4+ ) / ∑ M 4+ ,in, NBO represents all tetrahedral coordination O 2- The total number of T represents the total number of tetrahedral network-building cations, NBO Divide by T It is the non-bridging oxygen index.

[0011] In a specific embodiment, in step S4, the specific steps of back-calculating the concentration of peroxygen defects according to the non-bridging oxygen index include: S41, calculated based on the non-bridging oxygen index of the mineral NBO / T , first calculate the O - The extra negative charge is shared by the tetrahedral net-building cations. R for: R =4- NBO / T ; S42, then according to the total concentration of tetrahedral network-building cations ∑ M 4+ and the shared index R , calculate the total concentration of oxygen concentration defects in the mineral PHP for: PHP= ∑M 4+ × R .

[0012] Beneficial effects of the invention: The method of the invention is based on the fact that minerals are doped during their formation. O - The structure of the mineral will then change the principle of the non-bridging oxygen index of the mineral. The concentration of each ion in the mineral is first measured, and then the non-bridging oxygen index of the mineral is calculated. Finally, the concentration of peroxygen defects in the mineral is quantitatively calculated based on the non-bridging oxygen index. This can realize the quantitative analysis of peroxygen defects in minerals, and provide a new method for the quantitative study of peroxygen defects in earth minerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Flow chart of the method of the present invention.

[0014] Figure 2 Schematic diagram of the silicon-oxygen tetrahedron structure.

[0015] Figure 3 Schematic diagram of the structure of feldspar mineral.

[0016] Figure 4 Schematic diagram of the connection structure of peroxide defects in the silicon-oxygen tetrahedral structure. DETAILED DESCRIPTION

[0018] The present invention provides a method for calculating the concentration of peroxygen defects in earth minerals, comprising the following steps: See also Figure 1 First, the concentration of each oxide in the mineral is obtained by inductively coupled plasma emission spectrometry, and then the constant element ions are calculated according to the chemical molecular formula of each oxide. Na + , K + , Mg 2+ , Ca 2+ , Mn 2+ , Fe 2+ , Fe 3+ , Al 3+ , Ti 4+ , P 5+ , Si 4+ and O 2-Of course, in other embodiments, a whole rock analyzer can also be used to obtain the concentration of each oxide. The method of using a whole rock analyzer or an inductively coupled plasma emission spectrometer to obtain the concentration of each oxide in a mineral is a known technology.

[0019] Then, according to the calculated concentrations of each constant element ion, we get O 2- The concentration is ∑ M 2- , the total concentration of tetrahedral network-building cations is ∑ M 4+ , where ∑ M 4+ express Si 4+ and∑ M 3+ The concentration of the sum of M 3+ express Fe 3+ and Al 3+ The total concentration, or M 3+ Represents the total number of positive charges of network-changing cations in each valence state.

[0020] See also Figure 2 and Figure 3 , since the mineral is mainly composed of a tetrahedral structure, and the tetrahedral structure is composed of a network-building cation ( Si 4+ , Fe 3+ or Al 3+ ) Connect four O 2- Therefore, according to the concentration of each constant element ion obtained, the total concentration of tetrahedral network cations and O 2- The non-bridging oxygen index of the mineral can be calculated based on the concentration.

[0021] However, in calculating the total concentration of tetrahedral network-building cations ∑ M 4+ In the process, because the trivalent network-forming cations are variable valence ions, for example, Fe The elements exist Fe 2+ and Fe 3+ Two valence states, Fe 2+ Unstable, resulting in the measured Fe 3+ The concentration may be biased, so the total concentration of tetrahedral network-building cations is ∑M 4+ There is a deviation.

[0022] because Fe 3+ or Al 3+ In the tetrahedron formed by Fe 3+ or Al 3+ It can only consume 3 negative charges, while the 4 connected to it O 2- can provide 8 negative charges, which leads to Fe 3+ or Al 3+ Compared with the tetrahedron composed of Si 4+ The tetrahedron formed will have an extra negative charge, and this extra negative charge is passed through the variable net cation Na + , K + , Mg 2+ , Ca 2+ , Mn 2+ , Fe 2+ , Ti 4+ and P 5+ To balance the charge, so that the mineral is electrically neutral as a whole. Therefore, based on the principle that the mineral is electrically neutral as a whole, we can judge whether the Fe 3+ and Al 3+ The relationship between the extra negative charge of the tetrahedral structure and the total positive charge of each valence variable cation is used to adjust the calculated Fe 3+ and Al 3+ The value of the total concentration.

[0023] because Fe 3+ and Al 3+ The extra negative charge of the tetrahedral structure is Fe 3+ and Al 3+ The total concentration is the same, so the judgment is made by Fe 3+ and Al 3+ The tetrahedral structure composed of Si4+ The relationship between the extra negative charge of the tetrahedral structure and the total positive charge of each valence state variable cation is as follows: The total concentrations of the cations in each valence state are calculated to be ∑ M + ,∑ M 2+ and∑ Ti 4+ , where ∑ M + express Na + , K + and P 5+ The total concentration, ∑ M 2+ express Mg 2+ , Ca 2+ , Mn 2+ and Fe 2+ The total concentration, ∑ Ti 4+ express Ti 4+ The total concentration of Fe 3+ and Al 3+ The total concentration of each valence state of the cations is related to the total number of positive charges ∑ M + +2∑ M 2+ +4∑ Ti 4+ The relationship between: like Fe 3+ and Al 3+ Total concentration of M + +2∑ M 2+ +4∑ Ti 4+ , then take ∑ M + +2∑ M 2+ +4∑ Ti 4+ =∑ M 3+ , that is, M 3+ =∑ M + +2∑ M2+ +4∑ Ti 4+ , that is, the total positive charge of each valence state variable cation ∑ M 3+ Expressed as Fe 3+ and Al 3+ The total concentration of Fe 3+ and Al 3+ Total concentration ≤∑ M + +2∑ M 2+ +4∑ Ti 4+ , then ∑ M 3+ Directly expressed as Fe 3+ and Al 3+ total concentration.

[0024] Then, according to O 2- Concentration M 2- and the total concentration of tetrahedral network-building cations after adjustment∑ M 4+ , calculate the non-bridging oxygen index of the mineral NBO / T Values: NBO / T =(2∑ M 2- -4∑ M 4+ ) / ∑ M 4+ ,in, NBO represents tetrahedral coordination O 2- The total number of T represents the total number of tetrahedral network-building cations, NBO Divide by T It is the non-bridging oxygen index.

[0025] Each O 2- They only provide a negative charge to the network-building cation, thus forming O 2- Connection with net-making cation, a O 2- There is one negative charge remaining, that is, the numerator of the above formula is all O 2- The total amount of negative charge remaining after being consumed by all the net-building cations is equal to O 2-The total number of. The denominator ∑ M 4+ is the total concentration of tetrahedral network-building cations, that is, the total number of tetrahedrons. Therefore, NBO / T It is the non-bridging oxygen index of the mineral, that is, the average number of connected tetrahedra O 2- If the mineral is not doped O - The formation of peroxy defects means that the tetrahedral cations are connected O 2- According to the above formula, we can get NBO / T =4. If the mineral is doped O - The formation of peroxygen defects, see Figure 4 , which means O - Replaces one of the tetrahedrons O 2- location, and O - Compared to O 2- The number of negative charges provided is small, that is, the molecular part of the above formula should be smaller, thereby changing the non-bridging oxygen index.

[0026] Theoretically, one net-building cation in a tetrahedral structure connects four O 2- , that is, in an ideal state NBO / T =4. However, the mineral actually has peroxygen defects before sampling and testing. Although the peroxygen defects consist of 2 O - However, the peroxygen defect is force-sensitive, and the sampling process will cause the peroxygen defect in the mineral to break and release a mobile O - That is, one oxygen defect in the mineral corresponds to one remaining O - , which is equivalent to a peroxide defect doped with only one O - , doped O - Replaces the silicon-oxygen tetrahedron O 2- position, resulting in one net-making cation being able to connect only NBO / T indivual O 2- When there is O - When doped, the distribution of oxygen ions in the mineral structure changes. O - Replace the tetrahedron O 2- The position is equivalent to O 2-Loses a negative charge and becomes O - , these extra negative charges will be shared by all the network-building ions, that is, the negative charge index shared by each tetrahedral structure is R for: R =4- NBO / T .

[0027] And one O - Corresponding to an extra shared negative charge, the negative charge index shared by each tetrahedral structure is R This is equal to the doping in each tetrahedron O - The number of tetrahedral network-building cations is equal to the number of peroxygen defects. M 4+ and sharing index R , the total concentration of oxygen concentration defects in the mineral can be calculated PHP for: PHP= ∑ M 4+ × R .

[0028] This method is based on the fact that minerals will be doped during their formation. O - The formation of peroxide defects, which will only release one O - , which will change the principle of the non-bridging oxygen index of minerals. First, the concentration of each ion in the mineral is measured, and then the non-bridging oxygen index of the mineral is calculated. Finally, the concentration of mineral peroxygen defects is quantitatively calculated based on the non-bridging oxygen index. This can realize the quantitative analysis of peroxygen defects in minerals and provide a new method for the study of earth minerals.

[0029] To make it easier to understand the present solution, the present solution is further described below in conjunction with specific embodiments.

[0030] Example 1 Taking feldspar minerals as an example, since the water in the mineral in the molten state is structural water, it will participate in the silicon-oxygen tetrahedral structure, and its oxygen ions will participate in the charge balance. What we obtain through the inductively coupled plasma emission spectrometer is liquid water, so the measured mineral oxide concentration needs to be restored to the molten oxide concentration before calculation, so that the calculation result will be more accurate. The specific operation is as follows: Given that the peroxide defect formation temperature is approximately 800 K , so the feldspar melt temperature is set to 800 K The pressure and water fugacity of granite porphyry are 400×10 5 Pa and 370×105 Pa , first calculate the solubility of water in the mineral : in, A =-34345.9, B =18.3527, =4500, The calculation can be obtained: is -30.5903, is 0.1096. According to the above formula, we can get: Using numerical approximation method, we can get: =0.0861 or =8.61 mol %.

[0031] Then, the concentration of each oxide in the feldspar mineral is obtained by inductively coupled plasma emission spectrometry, and the oxides include: SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO , K 2 O , MgO , Na 2 O , TiO 2 and H 2 O Since the mineral contains components that volatilize during the cooling and crystallization process, it is necessary to calculate the content of the volatile components in the melt after it is restored (this experiment only considers ), that is, the oxide concentration obtained should also be adjusted, and the adjustment formula is: in, i represents oxides, such as SiO 2 , Al 2 O 3 wait, dIndicates the mineral state, X i d represents the measured mineral oxide concentration, X i Indicates the concentration of oxide adjusted to the molten state.

[0032] The adjusted concentration results of each oxide, as well as the concentration results of cations and anions in each oxide calculated according to the chemical molecular formula of each oxide, that is, the concentration of major element ions in the mineral, are shown in Table 1.

[0033] Table 1 shows the calculation process and results of the concentrations of each oxide and its cation and anion. Then, according to the concentration of each constant element ion calculated in Table 1, we can calculate O 2- The total concentration is ∑ M 2- =2678.555 mol The total concentration of each valence state network cation is ∑ M + =130.394 mol ,∑ M 2+ =191.31 mol ,∑ Ti 4+ =4.275 mol Since FeO is easily oxidized to Fe2O3, Fe 2+ All Fe 3+ calculate.

[0034] From Table 1, we can calculate that M + +2∑ M 2+ +4∑ Ti 4+ =530.122 mol , and ∑ M 3+ =289.796 mol , because M 3+ <∑ M + +2∑ M 2+ +4∑ Ti 4+ , so Fe 3+ and Al 3+ The total concentration is taken as ∑M 3+ The value itself, that is Fe 3+ and Al 3+ The total concentration of M 3+ =289.796 mol The remaining network-modifying ions are in a free state and participate in other reactions.

[0035] The total concentration of the final tetrahedral net-building cations ∑ M 4+ =989.4 mol +289.796 mol =1279.196 mol ,according to NBO / T =(2∑ M 2- -4∑ M 4+ ) / ∑ M 4+ , the non-bridging oxygen index of the mineral can be calculated NBO / T is 0.1878, indicating that in this mineral, due to O - The doping makes it possible for each tetrahedron to connect only 0.1878 O 2- , the remaining negative charge is shared by all network-building ions, according to R =4- NBO / T The sharing index can be calculated R It is 3.8122.

[0036] According to PHP= ∑ M 4+ × R The total concentration of oxygen concentration defects in the mineral can be calculated PHP is 4.8765 mol .

[0037] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A method for calculating the concentration of peroxygen defects in earth minerals, characterized in that: The method comprises the following steps: S1. Obtain the concentration of each constant element ion in the mineral, wherein the constant element ions include: Na + , K + , Mg 2+ , Ca 2+ , Mn 2 + , Fe 2+ , Fe 3+ , Al 3+ , Ti 4+ , P 5+ , Si 4+ and O 2- ; S2. Calculate the total concentration of tetrahedral net-building cations and O 2- Concentration, get O 2- The concentration is ∑ M 2- , the total concentration of tetrahedral network-building cations is ∑ M 4+ , where ∑ M 4+ express Si 4+ and∑ M 3+ The concentration of the sum of M 3+ express Fe 3+ and Al 3+ The total concentration, or M 3+ represents the total positive charge of each valence state network cation; the total concentration of each valence state network cation is also calculated as ∑ M + ,∑ M 2+ and∑ Ti 4+ , where ∑ M + express Na + , K + and P 5+ The total concentration, ∑ M 2+ express Mg 2+ , Ca 2+ , Mn 2+ and Fe 2+ The total concentration, ∑ Ti 4+ express Ti 4+ The total concentration of M + +2∑ M 2+ +4∑ Ti 4+ That is, the total positive charge of each valence state variable cation; Fe 3+ and Al 3+ The total concentration of each valence state of the cations is related to the total number of positive charges ∑ M + +2∑ M 2+ +4∑ Ti 4+ The relationship between: If Fe 3+ and Al 3+ Total concentration of M + +2∑ M 2+ +4∑ Ti 4+ , then take ∑ M + +2∑ M 2+ +4∑ Ti 4+ =∑ M 3+ , that is, M 3+ =∑ M + +2∑ M 2+ +4∑ Ti 4+ Otherwise, if Fe 3+ and Al 3+ Total concentration ≤∑ M + +2∑ M 2+ +4∑ Ti 4+ , then M 3+ Pick Fe 3+ and Al 3+ The total concentration of S3, according to the total concentration of tetrahedral network cations and O 2- The concentration is used to calculate the non-bridging oxygen index of the mineral; S4. Reversely calculate the concentration of peroxygen defects based on the non-bridging oxygen index.

2. The method for calculating the concentration of peroxygen defects in earth minerals according to claim 1, characterized in that: In step S1, the specific steps of obtaining the concentration of each constant element ion in the mineral are: first obtaining the concentration of each oxide in the mineral, and then calculating the concentration of each constant element ion according to the chemical molecular formula of each oxide.

3. The method for calculating the concentration of peroxygen defects in earth minerals according to claim 2, characterized in that: In step S1, an inductively coupled plasma emission spectrometer or a whole rock analyzer is used to obtain the concentration of each oxide in the mineral.

4. The method for calculating the concentration of peroxygen defects in earth minerals according to claim 3, characterized in that: In step S3, according to O 2- Concentration M 2- and the total concentration of tetrahedral network-building cations∑ M 4+ , calculate the non-bridging oxygen index of the mineral NBO / T for: NBO / T =(2∑ M 2- -4∑ M 4+ ) / ∑ M 4+ ,in, NBO represents all tetrahedral coordination O 2- The total number of T represents the total number of tetrahedral network-building cations, NBO Divide by T It is the non-bridging oxygen index.

5. The method for calculating the concentration of peroxygen defects in earth minerals according to claim 4, characterized in that: In step S4, the specific steps of back-calculating the concentration of peroxygen defects according to the non-bridging oxygen index include: S41, calculated based on the non-bridging oxygen index of the mineral NBO / T , first calculate the O - The extra negative charge is shared by the tetrahedral net-building cations. R for: R =4- NBO / T ; S42, then according to the total concentration of tetrahedral network-building cations ∑ M 4+ and the shared index R , calculate the total concentration of oxygen concentration defects in the mineral PHP for: PHP= ∑ M 4+ × R .

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