Water source identification method for skarn iron deposits based on mineralization analysis

Abstract

The present invention relates to a water source identification method for a skarn iron ore deposit based on mineralization analysis, and relates to the technical field of water hazard prevention and control of skarn iron ore deposits, comprising the following steps: (1) determining the aquifer, aquiclude and corresponding lithologic belt of the skarn iron ore deposit; (2) determining the lithologic combination of each lithologic belt; detecting water samples of each aquifer respectively; analyzing the results of the lithologic combination and the water samples of each aquifer to determine the identification index of each aquifer; (3) when water inrush occurs in the skarn iron ore deposit, detecting the sum of the identification type constant components of the effluent water sample; comparing the water sample with the identification index of step (2), thereby determining the water source and runoff path of the water inrush. The present invention determines the representative water chemical characteristics of such a deposit from a mechanism perspective, determines the runoff path of groundwater through the water chemical characteristics, predicts the source of water inrush at the working face as early as possible, and takes corresponding water prevention and control measures in time to ensure the safe and efficient operation of the mine.

Description

Technical Field

[0001] The invention relates to the technical field of water hazard prevention and control of skarn-type iron ore deposits, and in particular to a water source identification method of skarn-type iron ore deposits based on mineralization analysis. Background Art

[0002] Mine water inrush is one of the main disasters in metal mining. Water inrush not only causes significant economic losses to mines, but also seriously threatens the lives of underground personnel and restricts safe and efficient production in mines. Timely identification of the main sources of underground water inrush, determination of the main runoff channels, and demarcation of water-rich areas on the top and bottom plates of the ore body are the key to water prevention and control in the infrastructure and mining stages of metal mines. It is also an important basis for reducing unnecessary exploration and drainage projects, reducing production costs, and improving the efficiency of mining and cutting projects.

[0003] Iron ore deposits in my country are usually divided into six types of genesis: sedimentary metamorphic, magmatic, skarn, volcanic, sedimentary and weathering leaching. Skarn iron ore is the most important type of rich iron ore deposit in my country. Skarn iron ore is mainly produced near the contact zone between the acidic intrusive rocks of the Yanshanian period and the carbonate strata containing gypsum salts ( Figure 1 ), is a typical magnetite ore body formed by hydrothermal replacement. The development of iron ore deposits is closely related to the gypsum salt layer in the overlying carbonate strata.

[0004] The evolution process of the hydrothermal (fluid) system from formation, storage, migration, circulation to precipitation is the formation process of skarn-type iron-rich deposits. With the circulation and migration of hydrothermal fluids, the material components are replaced between the rock mass and the carbonate surrounding rock. The rocks near the contact zone between the rock mass and the surrounding rock have undergone alteration stages such as dry skarnization, wet skarn-magnetite mineralization, and sulfide-carbonation. From the rock mass to the carbonate surrounding rock, it can be basically divided into four alteration zones: altered diorite zone, skarn zone, magnetite ore body zone (iron ore body), and altered carbonate rock zone, forming a unique rock combination zone of skarn-type iron deposits. The structure, texture, mineral and chemical composition of the rocks in each alteration zone are significantly different. The iron ore body is located between the alteration zones. The direct roof of the ore body is usually altered carbonate rock, that is, the karst aquifer is the direct water source of this type of ore deposit; the floor is usually skarn and altered diorite, and they are often distributed in an alternating manner. Therefore, skarn-type iron ore deposits are usually large water deposits, and the water-richness and hydrochemical characteristics of the roof and floor are different from those of coal mines and other types of iron ore deposits. In view of this, the present invention provides a method for distinguishing the water source of skarn-type iron ore deposits based on mineralization analysis. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for identifying the water source of a skarn-type iron ore deposit based on mineralization analysis. The purpose is to propose that the top carbonate aquifer and the bottom altered rock mass fissure aquifer of the skarn-type iron ore are two water sources for the ore deposit; to propose the constant components and proportional relationship of the groundwater in the two aquifers, δ 34 S value.

[0006] The technical solution of the present invention to solve the above technical problem is as follows: a method for identifying the water source of a skarn iron ore deposit based on mineralization analysis comprises the following steps:

[0007] (1) The aquifer, aquiclude and corresponding lithologic zones of the skarn iron ore deposit were determined, and it was found that the altered diorite zone constituted the bottom rock mass fissure aquifer, the skarn zone and magnetite ore body zone constituted the middle aquiclude, and the altered carbonate rock zone constituted the top karst aquifer;

[0008] (2) Determine the lithologic combination of the altered diorite belt and the altered carbonate belt; test the rock fissure water in the floor rock fissure aquifer, the karst water in the roof karst aquifer, and the mixed water formed after the karst water in the roof karst aquifer flows through the skarn belt and / or the magnetite ore body belt; analyze the lithologic combination of the altered diorite belt and the altered carbonate belt and the test results of water samples from each aquifer to determine the discrimination index of each aquifer;

[0009] (3) When water inrush occurs in skarn iron ore deposits, the effluent samples are analyzed for the identification of constant components and δ 34 S value detection; compare the test results of the effluent water sample with the discrimination index of each aquifer established in step (2) to determine the source of the sudden water and the runoff path.

[0010] The beneficial effects of the present invention are as follows: unlike other types of metal deposits and coal mines, the unique mineralization process and mineralization of skarn iron deposits determine that the hydrogeochemical characteristics of the main aquifers of such deposits are also unique; therefore, the present invention carries out the identification of the hydrochemical characteristics of the aquifer based on mineralization (identifying constant components and δ 34 S value detection) and underground water gushing source tracing can determine the representative hydrochemical characteristics of such deposits from a mechanism perspective, judge the runoff path of groundwater through hydrochemical characteristics, predict the source of water gushing at the working face early, and take corresponding water prevention and control measures in time to prevent vertical and lateral water inrush accidents on the top and bottom plates of the tunnels, minimize the loss of personnel and property caused by water disasters, and ensure the safe and efficient operation of mines. At the same time, the mineralization and mechanism of skarn-type iron deposits are similar. Therefore, the hydrogeological conditions and hydrochemical characteristics of typical skarn-type iron deposits in North China and the middle and lower reaches of the Yangtze River are also consistent. The present invention is applicable to skarn-type iron deposits.

[0011] Based on the above technical solution, the present invention can also be improved as follows.

[0012] Furthermore, step (1) includes the following specific steps: by investigating the water outlet points of the skarn-type iron ore deposit and recording the core, the aquifer, aquiclude and corresponding lithological zones of the skarn-type iron ore deposit are determined, and it is obtained that the altered diorite zone constitutes the bottom rock body fissure aquifer, the skarn zone and the magnetite ore body zone constitute the middle aquiclude, and the altered carbonate rock zone constitutes the top karst aquifer.

[0013] The beneficial effects of adopting the above further scheme are: the main aquifers and aquicludes of the skarn-type iron ore deposits are revealed through the water production situation, and the corresponding relationship between the water-richness and permeability of the aquifers and the altered rock belts is revealed; the main altered rock belts are determined through core logging; among them, the altered diorite belt constitutes the bottom rock fissure aquifer of the mine water-bearing system, which is a weak to medium aquifer; the altered carbonate rock belt constitutes the top karst aquifer, which is a strong aquifer; under natural conditions without mining damage, groundwater flows nearly horizontally in the aquifer.

[0014] Further, step (2) includes the following specific steps:

[0015] (2-1) Through optical thin section identification, probe and XRD analysis, the lithology combination of the altered diorite belt and the altered carbonate belt was determined, and the soluble minerals and insoluble minerals of the altered diorite belt and the altered carbonate belt were obtained respectively;

[0016] (2-2) Determine the main water chemical components of rock mass fissure water, karst water and mixed water respectively through constant component and sulfur isotope test analysis; determine the type of mineral dissolution from which each main water chemical component originates based on the soluble minerals and insoluble minerals of each lithological zone obtained in step (2-1);

[0017] (2-3) By analyzing the role of soluble minerals in different mineralization stages from high temperature to low temperature, and the fractionation of sulfur isotopes during the reaction and transformation of soluble minerals, the mechanism of the formation of the chemical characteristics of rock fissure water, karst water and mixed water can be determined, thereby determining the characteristic constant components and sulfur isotope composition characteristics of rock fissure water, karst water and mixed water; based on the characteristic constant components and sulfur isotope composition characteristics, the discrimination indicators of each aquifer can be determined.

[0018] Further, in step (2-3), the identified constant component includes Na + , K + , Ca 2+ Mg 2+ 、SO 4 2- , CO 3 2- , HCO 3 -and at least four of the total dissolved solids (TDS).

[0019] Furthermore, the discrimination index includes the content of each identified constant component, the equivalent percentage of each identified constant component, (Ca 2+ +Na + -Cl - ) / SO 4 2- The ion ratio coefficient (CO 3 2- +HCO 3 - ) / SO 4 2- The ion ratio coefficient, [(CO 3 2- +HCO 3 - ) / SO 4 2- )] / TDS ion ratio coefficient, δ 34 At least one of the values ​​of S.

[0020] Furthermore, the rock mass fissure water identification index includes at least one of the following: the type of rock mass fissure water is Ca-SO 4 and Ca·Mg-SO 4 Type, TDS is 1400mg / L~2400mg / L, δ 34 The value of S is 28.0‰~33.8‰, SO 4 2- Milligram equivalent percentage more than 85%, (CO 3 2- +HCO 3 - ) / SO 4 2- The ion ratio coefficient is less than 0.1.

[0021] Furthermore, the karst water identification index includes at least one of the following: the type of the karst water is Ca·Mg-HCO 3 Type, TDS less than 300mg / L, δ 34 The value of S is <13.7‰, (CO 3 2- +HCO 3 - ) mg equivalent percentage is more than 60%, SO 4 2- Less than 2 milliequivalents, (CO 3 2- +HCO 3 - ) / SO 42- The ion ratio coefficient is greater than 1.0.

[0022] Furthermore, the mixed water identification index includes at least one of the following: the type of the mixed water is Ca·Mg-HCO 3 ·SO 4 、Ca·Mg-SO 4 ·HCO 3 Type water, TDS is 300mg / L~800mg / L, δ 34 The value of S is 20.0‰~26.3‰, HCO 3 - The milligram equivalent percentage is between 55% and 10%, SO 4 2- The milligram equivalent percentage is 40%~85%, (CO 3 2- +HCO 3 - ) / SO 4 2- The ion ratio coefficient is less than 1.0.

[0023] Further, step (3) specifically includes:

[0024] (3-1) When water inrush occurs in skarn iron ore deposits, water samples are collected;

[0025] (3-2) The collected effluent samples were analyzed for the identification of constant components and δ 34 S value detection, the identification constant components and δ 34 The S value test results are compared with various discrimination indicators to determine the source of the sudden water and the runoff path.

[0026] Further, step (3-2) specifically includes the following steps: performing identification of constant components and δ 34 S value detection, according to the collected water sample identification constant components, calculate (Ca 2+ +Na + -Cl - ) / SO 4 2- Ion ratio coefficient, (CO 3 2- +HCO 3 - ) / SO 4 2- Ion ratio coefficient, [(CO 3 2- +HCO 3 - ) / SO 4 2-)] / TDS ion ratio coefficient, and compare it with each discrimination index through diagram, and use δ 34 The value of S further determines the comparison results, thereby determining the source of the sudden water and the runoff path. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The schematic diagram of the cross section of an iron ore exploration line in the Handan-Xingtai area of ​​the present invention; wherein 1 is the Quaternary gravel layer; 2 is the Carboniferous shale; 3 is the Middle Ordovician limestone (altered diorite belt); 4 is the gypsum breccia; 5 is the skarn; 6 is the iron ore body; 7 is the altered diorite belt; 8 is the borehole; 9 is the fault;

[0028] Figure 2 The optical thin section microscopic identification display diagram of the present invention; wherein, a is single polarized light, and together with magnetite, gypsum has negative protrusions, and anhydrite has neutral protrusions; b is orthogonal polarized light, gypsum has a first-level gray-white interference color, and anhydrite has a blue interference color; c is single polarized light, radial gypsum, gypsum aggregate; d is orthogonal polarized light, first-level gray-white interference color, gypsum develops around the calcite vein or in the gap; e is single polarized light, a small amount of gypsum develops in the calcite vein, and gypsum replaces the calcite vein; f is orthogonal polarized light, gypsum has a first-level gray-white interference color, and a piece of blue beside the vein is anhydrite;

[0029] Figure 3 is the XRD diagram of the soluble salt of the present invention; wherein a is the XRD interpretation diagram of the soluble salt separated from the skarn belt, and b is the XRD interpretation diagram of the soluble salt separated from the ore belt;

[0030] Figure 4 The Piper three-line diagram of each water gushing point of the present invention;

[0031] Figure 5 The relationship diagram of the ion ratio of the mine water and the sulfate mineral dissolution curve of the present invention;

[0032] Figure 6 is the ion ratio diagram of each water inflow point of the present invention; wherein a is each water inflow point (CO 3 2- +HCO 3 - ) / SO 4 2- Ion ratio diagram; b is the water inflow point [(CO 3 2- +HCO 3 - ) / SO 4 2- )] / TDS relationship diagram. DETAILED DESCRIPTION

[0033] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in this field or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased through regular channels.

[0034] The present invention uses water samples collected from the altered carbonate rock belt as karst water samples, water samples collected from the altered diorite belt, skarn layer or mineral layer as rock fissure water, also known as (ore body) water samples, and water samples from water gushing points after the tunnel roof and edge rupture as a type of samples, and further analyzes their classification and runoff path through water chemistry. Example

[0035] This embodiment relates to a method for identifying the water source of a skarn iron ore deposit based on mineralization analysis, comprising the following steps:

[0036] (1) The aquifer, aquiclude and corresponding lithologic zones of the skarn iron ore deposit were determined, and it was found that the altered diorite zone constituted the bottom rock mass fissure aquifer, the skarn zone and magnetite ore body zone constituted the middle aquiclude, and the altered carbonate rock zone constituted the top karst aquifer;

[0037] Preferably, step (1) of this embodiment includes the following specific steps: by investigating the water outlet points of the skarn-type iron ore deposit and recording the core, the aquifer, aquiclude and corresponding lithological zones of the skarn-type iron ore deposit are determined, and the altered diorite zone constitutes the bottom rock fissure aquifer, the skarn zone and the magnetite ore body zone constitute the middle aquiclude, and the altered carbonate rock zone constitutes the top karst aquifer.

[0038] Geological drilling, drainage holes, and tunneling projects have revealed that the direct water sources of skarn-type iron ore deposits include not only the top karst aquifer of the altered carbonate belt in the upper plate of the ore body, but also the bottom rock fissure aquifer composed of the altered diorite belt in the lower plate of the ore body, which is different from the previous understanding of rock impermeability. Among them, the altered carbonate belt and the altered diorite belt are aquifers. The altered carbonate aquifer has a large number of vertical and horizontal fissures, as well as pores formed by hydrothermal melting, and is highly water-rich and permeable; the fissure aquifer in the altered diorite belt is weak to medium in water-richness, weak to medium in permeability, small inflow, and basically unpressurized. The skarn belt and the magnetite ore body belt have become relatively impermeable layers due to factors such as dense block structure, calcareous cementation, and a large amount of fine-grained clay minerals.

[0039] (2) Determine the lithologic combination of the altered diorite belt and the altered carbonate belt; test the rock fissure water in the floor rock fissure aquifer, the karst water in the roof karst aquifer, and the mixed water formed after the karst water in the roof karst aquifer flows through the skarn belt and / or the magnetite ore body belt; analyze the lithologic combination of the altered diorite belt and the altered carbonate belt and the test results of each aquifer to determine the discrimination index of each aquifer;

[0040] In this embodiment, step (2) preferably includes the following specific steps:

[0041] (2-1) Through optical thin section identification, probe and XRD analysis, the lithology combination of the altered diorite belt and the altered carbonate belt was determined, and the soluble minerals and insoluble minerals of the altered diorite belt and the altered carbonate belt were obtained respectively;

[0042] (2-2) Determine the main water chemical components of rock mass fissure water, karst water and mixed water respectively through constant component and sulfur isotope test analysis; determine the type of mineral dissolution from which each main water chemical component originates based on the soluble minerals and insoluble minerals of each lithological zone obtained in step (2-1);

[0043] (2-3) By analyzing the role of soluble minerals in different mineralization stages from high temperature to low temperature, and the fractionation of sulfur isotopes during the reaction and transformation of soluble minerals, the mechanism of the formation of the chemical characteristics of rock fissure water, karst water and mixed water can be determined, thereby determining the characteristic constant components and sulfur isotope composition characteristics of rock fissure water, karst water and mixed water; based on the characteristic constant components and sulfur isotope composition characteristics, the discrimination indicators of each aquifer can be determined.

[0044] In this embodiment, preferably, in step (2-3), the marker constant component includes Na + , K + , Ca 2+ Mg 2+ 、SO 4 2- , CO 3 2- , HCO 3 - and total dissolved solids (TDS).

[0045] The location of the water sample and the water chemistry type are obtained from the projection diagram of these identified constant components (Piper three-line diagram), and the milligram equivalent ratio relationship diagram is obtained from the conventional ions: (Ca 2+ +Na + -Cl - ) / SO 4 2- Figure, (CO 3 2- +HCO3 - )-SO 4 2- Figure, (CO 3 2- +HCO 3 - / SO 4 2- )-TDS graph, and determine the aquifer from which the water sample comes according to the diagram. In this embodiment, the discrimination index preferably includes the content of each marker constant component, the equivalent percentage of each marker constant component, (Ca 2+ +Na + -Cl - ) / SO 4 2- The ion ratio coefficient (CO 3 2- +HCO 3 - ) / SO 4 2- The ion ratio coefficient, [(CO 3 2- +HCO 3 - ) / SO 4 2- )] / TDS ion ratio coefficient, δ 34 At least one of the values ​​of S.

[0046] In this embodiment, the rock mass fissure water, the karst water and the mixed water are preferably distinguished by the following indicators:

[0047] 1) The rock mass fissure water identification index is as follows: including at least one of the following: the type of rock mass fissure water is Ca-SO 4 and Ca·Mg-SO 4 Type, TDS is 1400mg / L~2400mg / L, δ 34 The value of S is 28.0‰~33.8‰, SO 4 2- Milligram equivalent percentage more than 85%, (CO 3 2- +HCO 3 - ) / SO 4 2- The ion ratio coefficient is less than 0.1.

[0048] 2) The karst water identification index includes at least one of the following: the type of karst water is Ca·Mg-HCO 3 Type, TDS less than 300mg / L, δ 34 The value of S is <13.7‰, (CO3 2- +HCO 3 - ) mg equivalent percentage is more than 60%, SO 4 2- Less than 2 milliequivalents, (CO 3 2- +HCO 3 - ) / SO 4 2- The ion ratio coefficient is greater than 1.0.

[0049] 3) The mixed water identification index includes at least one of the following: the type of the mixed water is Ca·Mg-HCO 3 ·SO 4 、Ca·Mg-SO 4 ·HCO 3 Type water, TDS is 300mg / L~800mg / L, δ 34 The value of S is 20.0‰~26.3‰, HCO 3 - The milligram equivalent percentage is between 55% and 10%, SO 4 2- The milligram equivalent percentage is 40%~85%, (CO 3 2- +HCO 3 - ) / SO 4 2- The ion ratio coefficient is less than 1.0.

[0050] Specifically, in this embodiment, the groundwater identification of two aquifers includes the following specific steps:

[0051] (a) Regional and mining area geological survey: core and tunneling chamber (tunnel) sampling, identification of minerals under optical thin section microscope, determination of sulfate minerals by probe and XRD, selection of pyrite and gypsum (anhydrite, celestite, barite) from probe slices for δ 34 S value;

[0052] (b) Verify the strata of each water-producing point in the well, sample the groundwater of the two main aquifers, and test the conventional components and δ 34 S: Calculate milligram equivalent (meq / L), milligram equivalent percentage, TDS and other indicators of constant component ions;

[0053] (c) Index analysis and graphic discrimination: Piper three-line diagram projection, drawing ion ratio coefficient diagram, analyzing the characteristics and differences of groundwater in each aquifer, combining the δ 34S value, determine the characteristic indicators, characteristic ions and proportional relationships of each aquifer, and thus determine the source of the water.

[0054] Among them, in step (a), the rock mass (ore body) is sampled and made into optical thin sections and probe sections, and the optical thin section microscopic identification shows ( Figure 2 a, 2b, 2c, 2d, 2e, 2f), gypsum and anhydrite are developed around magnetite and in the gaps of calcite veins. Gypsum and anhydrite associated with magnetite were formed in the wet skarn-magnetite stage, which is the same period as the formation of magnetite. Gypsum in the gaps of calcite veins was formed later than calcite and was formed under low temperature conditions in the late hydrothermal period.

[0055] In step (a), the rock (ore) sample is ground, soaked, and evaporated to obtain soluble salt, wherein each kilogram of rock contains 5 to 10 grams of soluble salt. The soluble salt powder is identified by XRD ( Figure 3 ab), mainly sulfates, chlorides and carbonates

[0056] In step (a), in order to determine the source of sulfate minerals in the rock mass and ore body belt, in situ sulfur isotope tests were conducted on pyrite and gypsum in the two rock belts. The pyrite was generally high, and δ 34 The S value ranges from 13.98‰ to 22.21‰ (Table 1). 34 The S value is obviously higher, far greater than the range of magmatic sulfur, and shows that the earlier the pyrite is formed, the higher the temperature, the better the crystal shape, and the δ 34 The higher the S value, the more the fractionation characteristics of the reaction change with temperature, indicating that sulfur has been added in the medium and high temperature stage. During the migration and circulation of the ore-forming fluid between the rock mass and the surrounding rock, sulfate from the marine sedimentary gypsum layer in the altered carbonate belt is mixed into the fluid.

[0057] Delta values ​​of gypsum and anhydrite minerals in altered diorite belts (altered diorite (ore bodies)) 34 The S value is between 24.0‰ and 33.1‰, which is consistent with the marine evaporative gypsum sulfur in the Ordovician strata of the North China Plate and has the sulfur isotope characteristics of marine evaporative sediments.

[0058] Table 1 Pyrite sulfur isotope δ in rock mass (ore body) 34 S value test results

[0059]

[0060] Delta of pyrite 34 The S value is between that of magmatic sulfur and marine sedimentary gypsum sulfur, indicating that the ore-forming hydrothermal fluids absorbed the δ 34 S, deposited gypsum participates in mineralization. Gypsum plays the role of oxidant in the formation of magnetite, and part of SO in sulfate 42- Experienced by Fe 2+ Reduction to H 2 S, HS - , S 2- The process of 2- with Fe 2+ Generate pyrite, in SO 4 2- H 2 SHS - S 2- In the transition from high price to low price, δ 34 S gradually decreases, that is, the gypsum and pyrite generated at the same time are fractionated. The fractionation coefficient is related to the temperature of the fluid. The higher the temperature, the smaller the fractionation value; the lower the temperature, the larger the fractionation value. Generally, below 250℃, SO 4 2- Fe 2+ Restore to S 2- The fractionation value of Δ≈15‰ is consistent with the fractionation values ​​of most gypsum and pyrite measured by the present invention, indicating that sedimentary gypsum participates in mineralization. The gypsum and pyrite in the rock body (ore body) are generated after sedimentary gypsum is mixed with hydrothermal fluid. 34 S reflects the characteristics of marine sedimentary sulfur.

[0061] In step (b), water samples from each aquifer are collected from typical skarn iron ore in the Hanxing area for conventional component and 34 S test (Table 2). Karst water (No. 1, 2, 3) δ 34 The value of S is lower than 13.7‰, and the rock mass fissure water (No. 13, 14, 15, 16, 17, 18) δ 34 The value of S is between 28.0 and 33.8‰, and the mixed water (No. 4 to 12) δ 34 The value of S is between 20.0 and 26.3‰. 34 The value of S is consistent with the sulfur isotope signature of the Middle Ordovician marine evaporative sedimentary gypsum salt. 34 The value of S is relatively high, ranging from 28.0 to 33.8‰; while δ 34 The value of S is relatively low, which is consistent with the δ 34 The similar values ​​of S indicate that during the hydrothermal mineralization process, most of the gypsum sulfur in the Middle Ordovician has been brought into the rock mass (ore body) by hydrothermal fluids or later groundwater, and very little gypsum remains in the carbonate surrounding rocks in the mining area.

[0062] At room temperature, gypsum reacts with SO in solution. 4 2- The isotopic fractionation between sulfide and sulfate is very low and can be basically ignored. The fractionation value of sulfide oxidation to sulfate is Δ≈0‰. Therefore, the high δ 34The S value mainly comes from the dissolution of sulfate in the rock mass, rather than the oxidation of pyrite in the rock mass. The sulfate in the altered diorite zone comes from the evaporated gypsum salt deposited in the Middle Ordovician. 34 S-type water is caused by the addition of sedimentary gypsum salt layers during the mineralization process, is determined by the mineralization of skarn iron deposits, and is the original water chemistry characteristic of rock fissure aquifers.

[0063] In step (b), the water sample collected from the water gushing point is subjected to conventional component testing to measure Na + , K + , Ca 2+ Mg 2+ 、SO 4 2- , CO 3 2- , HCO 3 - And TDS and other indicators, calculate the milligram equivalent (meq / L) of conventional ions, milligram equivalent percentage, calculate TDS and other indicators.

[0064] Table 2 Water samples from underground water inflow points of typical skarn iron mines in Hanxing area 34 S value test results

[0065]

[0066] In step (c), the ion components of all the water samples are projected into the Piper three-line diagram ( Figure 4 ), most of the water samples fall into zone 1. The main cations are Ca 2+ Mg 2+ , the anion is mainly HCO 3 - 、SO 4 2- According to the stratum of the water outlet, the water chemistry types range from karst water, mixed water to rock fissure water, and from Ca·Mg-HCO 3 (karst water), Ca·Mg-HCO 3 ·SO 4 (mixed water), Ca·Mg-SO 4 ·HCO 3 (mixed water) to Ca·Mg-SO 4 (rock fissure water), Ca-SO 4 (Rock fissure water) type.

[0067] In step (c), the main ions of each aquifer are different in that the groundwater in the altered carbonate zone is mainly carbonate dissolved, and the main anion is HCO 3 - , the main cation is Ca2+ Mg 2+ , TDS is usually less than 300 mg / L; rock fissure water is mainly dissolved in sulfates, and the main anions are SO 4 2- , the main cation is Ca 2+ , TDS is usually between 1400mg / L and 2400mg / L; the water in the tunnel roof and the border is mostly mixed, which is formed by karst water flowing through the rock mass (ore body), and the anions are HCO 3 - and SO 4 2- Mainly, HCO 3 - 、SO 4 2- The milligram equivalent percentage is between karst water and rock fissure water, and TDS is usually between 300mg / L and 800mg / L.

[0068] The groundwater type of altered carbonate belts is known and consistent in the North China Plate, and the Ca-SO 4 The fissure water of skarn-type rock mass is different from the usual fissure water type. Through the study of the mineralization process and mineralization of skarn-type iron ore, it was found that the Ca-SO 4 The formation mechanism of the type fissure water was determined by Ca-SO 4 Type water is its representative water chemistry type.

[0069] SO2 in groundwater of fractured aquifers 4 2- Mainly from the dissolution of sulfates such as calcium glauberite, gypsum, anhydrite and other minerals. Characteristic indicators (Ca 2+ +Na + -Cl - ) / SO 4 2- Ion ratio relationship ( Figure 5 ) shows that karst water, mixed water, and rock fissure water are all distributed along the 1:1 line of gypsum-salt dissolution, and sulfate dissolution exists in all of them. Karst water is above the 1:1 line, with low sulfate content and low milligram equivalent percentage. For karst water in an open environment, the stronger the runoff recharge effect, the higher the HCO 3 - The higher the content, the more the mixed water is above the 1:1 line. 3 - The content of SO 4 2- The mixed water sample point in the figure is close to the karst water, which means that the mixed water evolved from the karst water. When the karst water flows through a relatively closed rock or ore body, it mixes with sulfate and generates CaCO3 precipitation, because under closed conditions, the dissolved CO 2 The total amount of H in water is fixed. 2 CO 3 (aq), HCO 3 - , CO 3 2- The total amount of the three components is fixed, and as CaCO 3 The precipitation of HCO 3 - The water samples as a whole are close to the 1:1 line, and some are below the line. The locations of the rock mass fissure water injection points are far from the karst water and mixed water samples, and most of them are below the 1:1 line. 4 2- The main source of the pyrite oxidation is the dissolution of sulfate, which can basically exclude the source of pyrite oxidation. The rock mass zone is buried hundreds of meters underground, and the TDS of the rock mass fissure water is large, indicating that this zone is in a relatively stagnant environment, the groundwater flow rate is slow, and there is no oxidation condition for pyrite, which further indicates that the sulfate ions in the rock mass fissure water are not mainly formed by the oxidation of pyrite.

[0070] In step (c), according to (CO 3 2- +HCO 3 - ) / SO 4 2- Ion ratio, [(CO 3 2- +HCO 3 - ) / SO 4 2- )] / TDS diagram to determine the source of water and runoff path.

[0071] Figure 6 a Each water inflow point (CO 3 2- +HCO 3 - ) / SO 4 2- Ion ratio diagram; Figure 6 b Each water inflow point [(CO 3 2- +HCO 3 - ) / SO 4 2- )] / TDS relationship diagram. Figure 6 a and 6b, from (HCO 3 - +CO 3 2- )、SO 42- The respective milliequivalents, milliequivalent percentages, and (CO 3 2- +HCO 3 - ) / SO 4 2- The source of groundwater can be determined by the ratio of HCO 3 - SO 4 2- Mainly, (CO 3 2- +HCO 3 - ) / SO 4 2- The proportion of CaCO 3 CaSO 4 The solubility is small, when rich in HCO 3 - When karst water flows through sulfate-containing rock or ore bodies, CaCO 3 The precipitation of SO 4 2- The water volume of karst water and mixed water is gradually increasing, forming mixed water with karst water as the main body. The boundary between karst water and mixed water is not completely separated, but in a transitional state.

[0072] The karst water in the mining area has the same characteristics as the karst water in the North China Plate, mainly carbonate rock dissolution, and the main anion is HCO 3 - , (CO 3 2- +HCO 3 - ) mg equivalent percentage is more than 60%, SO 4 2- Usually less than 2 milliequivalents, and the milliequivalent percentage is less than 35%; (CO 3 2- +HCO 3 - ) / SO 4 2- Usually greater than 1.0. The cation is Ca 2+ Mg 2+ The water chemistry type is Ca·Mg-HCO 3 Type, TDS is usually less than 300mg / L; 34 The value of S is between <13.7‰.

[0073] The TDS and other indicators of mixed water are more similar to those of karst water. Initially, the mixed water is mainly carbonate rock dissolution. The mixed water is formed after karst water flows through the rock belt, skarn belt, and ore belt. The anions of mixed water are mainly HCO 3 - 、SO 4 2- As the sulfate content increases when flowing through the rock mass, the HCO 3 - The milliequivalent percentage decreased from 55‰ to 10‰, SO 4 2- The milligram equivalent percentage increased from 40‰ to 85‰, and the mixed water (CO 3 2- +HCO 3 - ) / SO 4 2- The ratio is usually less than 1.0, and the TDS is usually not high, ranging from 300mg / L to 800mg / L. 34 The value of S is between 20.0 and 26.3‰.

[0074] The hydrochemistry of rock mass fissure water is dominated by dissolved sulfates, and the anions in the water are mainly SO 4 2- , SO 4 2- Usually between 1000mg / L-1600mg / L, the milligram equivalent percentage is above 85%, (CO 3 2- +HCO 3 - ) mg equivalent percentages are all below 10%, (CO 3 2- +HCO 3 - ) / SO 4 2- The cations in rock mass fissure water are mainly Ca 2+ The water chemistry type is Ca-SO 4 and Ca·Mg-SO 4 Type, TDS is relatively high, between 1400mg / L~2400mg / L. 34 The value of S is between 28.0 and 33.8‰.

[0075] Rock mass fissure water is obviously different from karst water and mixed water. From the analysis of mineralization process and mineralization, SO 4 2-The dissolution of sulfate minerals such as gypsum, anhydrite, and calcium glauberite from the rock mass (ore body) belt. These sulfate minerals come from the sedimentary gypsum salt layer in the surrounding rock. After the sulfate in the gypsum salt layer enters the rock mass, skarn and ore body belt with the mineralization hydrothermal fluid, part of it is reduced to form pyrite, part of it is crystallized and precipitated with magnetite, and the remaining part is finally precipitated and remains in the gaps of the calcite veins in the rock mass belt (ore body belt) after the precipitation of calcite and other minerals as the hydrothermal temperature drops. Therefore, it can be comprehensively determined that the rock mass fissure water buried deep below the surface has poor circulation fluidity, high TDS, high SO 4 2- Content, high δ 34 The S value is the main indicator for determining the fissure water in the rock mass of skarn-type iron ore deposits.

[0076] Karst water usually flows horizontally along the underground karst zone. When the rock mass (ore body) is fractured due to mining excavation and mining, the karst water flows vertically through the fractured rock mass zone, and the water chemical composition changes, forming mixed water. From the detailed characteristics of water chemistry changes, it is also possible to further determine the runoff channel of groundwater, determine whether new fractures have occurred in the rock mass, and predict whether caving will occur.

[0077] (3) When water inrush occurs in skarn iron ore deposits, the effluent samples are analyzed for the identification of constant components and δ 34 S value detection; compare the test results of the effluent water sample with the discrimination index of each aquifer established in step (2) to determine the source of the sudden water and the runoff path.

[0078] In this embodiment, step (3) specifically includes:

[0079] (3-1) When water inrush occurs in skarn iron ore deposits, water samples are collected;

[0080] (3-2) The collected effluent samples were analyzed for the identification of constant components and δ 34 S value detection, the identification constant components and δ 34 The S value test results are compared with various discrimination indicators to determine the source of the sudden water and the runoff path.

[0081] Further, step (3-2) specifically includes the following steps: performing identification of constant components and δ 34 S value detection, according to the collected water sample identification constant components, calculate (Ca 2+ +Na + -Cl - ) / SO 4 2- Ion ratio coefficient, (CO 3 2- +HCO 3- ) / SO 4 2- Ion ratio coefficient, [(CO 3 2- +HCO 3 - ) / SO 4 2- )] / TDS ion ratio coefficient, and compare it with each discrimination index through diagram, and use δ 34 The value of S further determines the comparison results, thereby determining the source of the sudden water and the runoff path.

[0082] In summary, unlike other types of metal deposits and coal mines, the unique mineralization process and mineralization of skarn iron deposits determine that the hydrogeochemical characteristics of the main aquifers of this type of deposits are also unique; therefore, the present invention carries out the identification of the hydrochemical characteristics of the aquifer based on mineralization (identifying constant components and δ 34 S value) and underground water gushing source tracing can determine the representative hydrochemical characteristics of such deposits from a mechanism perspective, judge the runoff path of groundwater through hydrochemical characteristics, predict the source of water gushing at the working face early, take corresponding water prevention and control measures in time, prevent vertical and lateral water inrush accidents on the top and bottom plates of the tunnels, minimize the loss of personnel and property caused by water disasters, and ensure the safe and efficient operation of mines. At the same time, the mineralization and mechanism of skarn iron deposits are similar. Therefore, the hydrogeological conditions and hydrochemical characteristics of typical skarn iron deposits in North China and the middle and lower reaches of the Yangtze River are also consistent. The present invention is applicable to skarn iron deposits.

[0083] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for identifying water sources of skarn-type iron ore deposits based on mineralization analysis, characterized in that: The steps include: (1) The aquifer, aquiclude and corresponding lithologic zones of the skarn iron ore deposit were determined, and it was found that the altered diorite zone constituted the bottom rock mass fissure aquifer, the skarn zone and magnetite ore body zone constituted the middle aquiclude, and the altered carbonate rock zone constituted the top karst aquifer; (2) Determine the lithologic combination of the altered diorite belt and the altered carbonate belt; test the rock fissure water in the floor rock fissure aquifer, the karst water in the roof karst aquifer, and the mixed water formed after the karst water in the roof karst aquifer flows through the skarn belt and / or the magnetite ore body belt; conduct comparative analysis on the lithologic combination of the altered diorite belt and the altered carbonate belt and the test results of each aquifer to determine the discrimination index of each aquifer; (3) When water inrush occurs in skarn iron ore deposits, the effluent samples are analyzed for the identification of constant components and δ 34 S value detection; comparing the test results of the effluent water sample with the discrimination index of each aquifer established in step (2), so as to determine the source of the water inrush and the runoff path; Step (2) includes the following specific steps: (2-1) Through optical thin section identification, probe and XRD analysis, the lithology combination of the altered diorite belt and the altered carbonate belt was determined, and the soluble minerals and insoluble minerals of the altered diorite belt and the altered carbonate belt were obtained respectively; (2-2) Determine the main water chemical components of rock mass fissure water, karst water and mixed water respectively through constant component and sulfur isotope test analysis; determine the type of mineral dissolution from which each main water chemical component originates based on the soluble minerals and insoluble minerals of each lithological zone obtained in step (2-1); (2-3) By analyzing the role of soluble minerals in different mineralization stages from high temperature to low temperature, and the fractionation of sulfur isotopes during the reaction and transformation of soluble minerals, the formation mechanism of the chemical characteristics of rock fissure water, karst water and mixed water can be determined, thereby determining the signature constant components and sulfur isotope composition characteristics of rock fissure water, karst water and mixed water; According to the characteristics of the marker constant components and sulfur isotope components, the identification indexes of each aquifer are determined; The discrimination indexes include the content of each identified constant component, the equivalent percentage of each identified constant component, (Ca 2+ +Na + -Cl - ) / SO4 2- The ion ratio coefficient, (CO3 2- +HCO3 - ) / SO4 2- The ion ratio coefficient, [(CO3 2- +HCO3 - ) / SO4 2- )] / TDS ion ratio coefficient, δ 34 at least one of the values ​​of S, wherein the TDS is expressed as total dissolved solids; The rock mass fissure water identification indexes include: the rock mass fissure water type is Ca-SO4 and Ca·Mg-SO4, TDS is 1400mg / L~2400mg / L, δ 34 The value of S is 28.0‰~33.8‰, SO4 2- Milligram equivalent percentage is more than 85%, (CO3 2- +HCO3 - ) / SO4 2- The ion ratio coefficient is less than 0.1; The karst water identification indexes include: the type of karst water is Ca·Mg-HCO3 type, TDS is less than 300 mg / L, δ 34 The value of S is <13.7‰, (CO3 2- +HCO3 - ) mg equivalent percentage is more than 60%, SO4 2- Less than 2 mg equivalent, (CO3 2- +HCO3 - ) / SO4 2- The ion ratio coefficient is greater than 1.0; The mixed water identification index includes: the type of the mixed water is Ca·Mg-HCO3·SO4, Ca·Mg-SO4·HCO3 type water, TDS is 300mg / L ~ 800mg / L, δ 34 The value of S is 20.0‰~26.3‰, HCO3 - The milligram equivalent percentage is between 55% and 10%, SO4 2- The milligram equivalent percentage is 40%~85%, (CO3 2- +HCO3 - ) / SO4 2- The ion ratio coefficient is less than 1.

0.

2. The method for identifying the water source of a skarn iron ore deposit based on mineralization analysis according to claim 1, characterized in that: Step (1) comprises the following specific steps: determining the aquifer, aquiclude and corresponding lithologic zones of the skarn-type iron ore deposit by investigating the water outlet points of the skarn-type iron ore deposit and recording the cores, obtaining that the altered diorite zone constitutes the bottom rock mass fissure aquifer, the skarn zone and the magnetite ore body zone constitute the middle aquiclude, and the altered carbonate zone constitutes the top karst aquifer.

3. The method for identifying the water source of a skarn iron ore deposit based on mineralization analysis according to claim 1, characterized in that: In step (2-3), the marker constant component includes Na + , K + , Ca 2+ Mg 2+ 、SO4 2- 、CO3 2- 、HCO3 - and at least four of the total dissolved solids.

4. The method for identifying the water source of skarn-type iron ore deposits based on mineralization analysis according to claim 1, characterized in that: Step (3) specifically includes: (3-1) When water inrush occurs in skarn iron ore deposits, water samples are collected; (3-2) The collected effluent samples were analyzed for the identification of constant components and δ 34 S value detection, the identification constant components and δ 34 The S value test results are compared with various discrimination indicators to determine the source of the sudden water and the runoff path.

5. The method for identifying the water source of skarn-type iron ore deposits based on mineralization analysis according to claim 4, characterized in that: Step (3-2) specifically includes the following steps: the collected effluent water samples are analyzed for the identification constant components and δ 34 S value detection, according to the collected water sample identification constant components, calculate (Ca 2+ +Na + -Cl - ) / SO4 2- Ion ratio coefficient, (CO3 2- +HCO3 - ) / SO4 2- Ion ratio coefficient, [(CO3 2- +HCO3 - ) / SO4 2- )] / TDS ion ratio coefficient, and compare it with each discrimination index through diagram, and use δ 34 The value of S further determines the comparison results, thereby determining the source of the sudden water and the runoff path.

Images