阅读说明：本技术 一种离子型稀土矿小药量空气间隔***增渗方法 (Ionic rare earth ore small-dosage air interval blasting permeation increasing method ) 是由 刘连生 于 2019-10-14 设计创作，主要内容包括：本发明公开了一种离子型稀土矿爆破增渗的方法,旨在离子型稀土矿体中实施小药量爆破,提高矿床渗透性能且保证矿体稳定。该方法涉及风化岩体精确控制爆破技术领域,包括如下步骤：步骤一,爆破区风化层矿床岩样采集和制备；步骤二,对岩样孔隙结构进行核磁共振扫描；步骤三,测定各组岩样单轴抗压强度；步骤四,对不同孔隙度岩样在分离式霍普金森压杆试验系统(SHPB)上进行冲击试验；步骤五,根据实验结果建立损伤演化模型,计算产生有效渗透率的冲击载荷大小,根据能量法换算炸药量和孔网参数。本发明以室内岩石动力学试验为手段,通过改变矿床孔隙结构提升渗透性,且保证的矿体稳定性,同时该发明还可应用于其他低渗透矿床爆破增渗设计。(The invention discloses a method for blasting and permeation-increasing of an ionic rare earth ore, aiming at implementing small-dosage blasting in an ionic rare earth ore body, improving the permeability of an ore deposit and ensuring the stability of the ore body. The method relates to the technical field of accurate control blasting of weathered rock mass, and comprises the following steps: collecting and preparing a weathered layer ore deposit rock sample in a blasting area; step two, performing nuclear magnetic resonance scanning on the pore structure of the rock sample; step three, measuring the uniaxial compressive strength of each group of rock samples; performing impact tests on rock samples with different porosities on a split Hopkinson pressure bar test System (SHPB); and step five, establishing a damage evolution model according to the experimental result, calculating the impact load size generating the effective permeability, and converting the explosive quantity and the pore network parameters according to an energy method. The method takes an indoor rock dynamics test as a means, improves the permeability by changing the pore structure of the ore deposit, ensures the stability of the ore body, and can also be applied to other low-permeability ore deposit blasting permeation-increasing designs.)

1. an ionic rare earth ore small-dosage air interval blasting permeation-increasing method is characterized in that: the method comprises the following steps:

Firstly, collecting and preparing a rock sample of a weathered layer ore deposit in a blasting area, excavating two to three rough blanks at different points in a rare earth weathered layer, wherein the size of the rough blanks is 1m multiplied by 0.5m, tightly binding the ore sample along the periphery by using bamboo chips and steel wires, slotting the bottom of the ore sample, inserting a wood board into the bottom of the ore sample, taking out the rough blanks of the ore sample, properly protecting and transporting the rough blanks of the ore sample to a laboratory, and processing the rough blanks of the ore sample into standard cylindrical rock test pieces of 50mm multiplied by 100mm (diameter multiplied by height), 50mm multiplied by 50mm (diameter multiplied by height) and 50mm multiplied by 25mm (diameter multiplied by height) in;

Performing nuclear magnetic resonance scanning on the pore structure of the rock sample, numbering the pore structure according to the size of the porosity, determining the internal pore distribution and the structural composition of the weathered rock by adopting a nuclear magnetic resonance transverse relaxation time spectrum and nuclear magnetic resonance imaging, and classifying the weathered rock according to the size of the pores;

step three, measuring the uniaxial compressive strength of each group of rock samples, testing the uniaxial compressive strength of rocks with different porosities, and determining the deterioration degree of the hydrostatic strength before and after the rocks are impacted by multiple explosions;

Performing impact tests on rock samples with different porosities on a split Hopkinson pressure bar test System (SHPB), wherein the impact tests mainly comprise single impact and multiple impacts, the single impact simulates the damage and permeability evolution law of rocks after different explosive quantities are impacted by explosion, and the multiple impacts simulate the influence on the damage and permeability of the rocks under differential interval blasting impact;

and step five, establishing a double-parameter damage evolution model according to the experimental result, determining the size of the impact load generating the effective permeability, converting the explosive quantity according to an energy method and designing the parameters of the mesh.

2. The ionic rare earth ore small-dosage air interval blasting infiltration increasing method according to claim 1, which is characterized in that: in the second step of the method, a core nuclear magnetic resonance spectrometer is adopted to carry out quantification and image analysis on the internal pore structure of the weathered granite, the change of the microscopic structure before and after impact is compared, and the influence of the evolution rule of the pore structure on the permeability is summarized.

3. The ionic rare earth ore small-dosage air interval blasting infiltration increasing method according to claim 1, which is characterized in that: in the fourth step of the method, the maximum and minimum impact energy which can be borne by the weathered granite is determined by single impact on the weathered granite, and the maximum dosage of a single section is converted; the selected size is 9.85J-52.65J incident energy equal amplitude cycle impact and four-stage loading impact at 12.80J, 20.3J, 27.25J and 37.92J respectively.

4. the ionic rare earth ore small-dosage air interval blasting infiltration increasing method according to claim 1, which is characterized in that: in the fifth step of the method, a model of energy conversion dosage is established, a test blasting network is designed according to geological exploration conditions and working conditions of a blasting area, and the model is optimized and calculated.

5. The ionic rare earth ore small-dosage air interval blasting infiltration increasing method according to claim 1, which is characterized in that: in the fourth step of the method, the multiple impact refers to 3 impacts with the incident energy of 12.80J, 20.3J and 27.25J at least.

Technical Field

the invention belongs to the technical field of accurate control blasting of weathered rock masses, and particularly relates to a method for determining blasting parameters in a low-permeability ionic rare earth ore blasting permeation-increasing indoor test.

Background

the ion-adsorption rare earth ore is a rare precious ore species in the world and is widely distributed in seven provinces (regions) of Jiangxi, Fujian, Hunan, Guangdong, Guangxi and Zhejiang in south China, and the ion-type rare earth in Gannan region of Jiangxi accounts for 32.4% of the proven reserves. The in-situ leaching mining method can realize 'green mining' of the ion adsorption type rare earth ore under the conditions of not damaging surface vegetation, not stripping surface soil and excavating mountain bodies. More than half of rare earth is collected and stored in 0.074mm ore particles accounting for 24-32% of the weight of raw ore, and the ore particles are fine in particle size, small in pore space and poor in permeability. The permeability of the ore is poor, and the leaching rate of the rare earth is not influenced, but the leaching time needs to be longer. The leaching liquid must be completely infiltrated into the whole weathered layer for fully recovering the rare earth, the whole leaching time lasts from several months to one year, and long-time leaching easily causes the rare earth ore body side slope to slide and even slide down, thereby causing casualties and property loss. One of the three possible conditions for in situ leaching of ionically adsorbed rare earths is the requirement for good permeability of the main deposit. In order to obtain proper permeability, reduce the leaching time of the rare earth ore, improve the leaching efficiency of the rare earth and reduce the accident environmental problem, the method provides that small-dosage air interval blasting is implemented in an ionic rare earth ore weathered layer to generate an explosion stress wave in a rare earth ore body so as to change the pore structure of the rare earth ore body and improve the permeability of the ore body.

Aiming at the low permeability deposit blasting permeability-increasing technology, the method has successful application in the aspects of oil and gas fields, coal bed gas exploitation, gas control, sandstone-type uranium ores and the like, and published documents are as follows: petroleum exploration and development, volume 28 (phase 2) in 2001, 90-96+106-113+123, research on "in-situ explosion" production increase technology in low permeability oil and gas fields "; the research on effective technical approaches for mining coal bed gas in low-permeability coal reservoirs on page 455-458 of volume 26 (5 th) of the journal of coal science, 2001; the research on the blasting infiltration model test and infiltration mechanism of low-permeability sandstone-type uranium deposit on pages 1609-1617 of volume 35 (phase 8) of the report on rock mechanics and engineering 2016. The technology is mainly applied to blasting and permeability increasing of deep rock mass without face empty face, the blasted rock mass is compact rock, and meanwhile, the restriction of stability of the ore body is small, but a certain foundation is laid for the application of the blasting and permeability increasing technology.

Compared with the method, the ionic rare earth ore exists in granite weathering crust, the ore body buries deeply and shallowly, the stability of the ore body is poor during ore leaching, the weathering degree of the rock body is high and the like, and the blasting infiltration increasing is adopted while the overall disturbance on the ore body is minimum, so that the ore body cannot be destabilized and collapsed. Therefore, a method for controlling blasting by accurately delaying time with small dosage is adopted, and reports of the application of the technology to the ionic rare earth ore are not seen so far.

disclosure of Invention

Aiming at the problem of low in-situ leaching efficiency of the ionic rare earth ore, the invention provides a small-dosage air interval blasting permeation-increasing method for the ionic rare earth ore, which aims to solve the problems of leaching efficiency and ore body stability.

The invention is realized by the following technical scheme:

The method comprises the following steps: and (3) collecting and preparing rock samples of the weathered layer ore deposit in the blasting area, and excavating two to three large rough blanks at different points in the rare earth weathered layer, wherein the size of each rough blank is about 1m multiplied by 0.5 m. The method comprises the following steps of fastening the ore sample by bamboo chips and steel wires along the periphery, slotting the bottom of the ore sample, inserting a wood board into the bottom of the ore sample, taking out at least 2 ore sample rough blanks, and carrying to a laboratory under proper protection. Standard 50mm × 100mm (diameter × height), 50mm × 50mm (diameter × height) and 50mm × 25mm (diameter × height) cylindrical rock test pieces were processed in a laboratory;

Step two: performing nuclear magnetic resonance scanning on the pore structure of the rock sample, numbering the pore structure according to the size of the porosity, determining the pore distribution and the structure composition in the weathered rock by adopting a nuclear magnetic resonance transverse relaxation time spectrum and nuclear magnetic resonance imaging, and classifying the pore distribution and the structure composition according to the size of the pores;

Step three: testing the uniaxial compressive strength of each group of rock samples, testing the uniaxial compressive strength of rocks with different porosities, and determining the deterioration degree of the hydrostatic strength before and after the rocks are impacted by multiple explosions;

Step four: performing impact tests on rock samples with different porosities on a split Hopkinson pressure bar test System (SHPB), wherein the impact tests mainly comprise single impact and multiple impacts, the single impact simulates the damage and permeability evolution law of rocks after different explosive quantities are impacted by explosion, and the multiple impacts simulate the influence on the damage and permeability of the rocks under differential interval blasting impact;

step five: and establishing a double-parameter damage evolution model according to the experimental result, determining the size of the impact load generating the effective permeability, converting the explosive quantity according to an energy method and designing the parameters of the mesh.

in order to better implement the method, in the first step of the method, the core drill is used for exploring the stratum condition of the explosion area to determine a representative sampling site.

to better practice the invention, it is further contemplated that in step four of the method, the effective incident energy of a single impact is determined to be 9.85J-52.65J, and the rock sample is effectively damaged without losing the bearing capacity under the explosive impact load in the range. Carrying out constant-amplitude and step-by-step multiple impacts on the rock sample in a bearing range, establishing a damage evolution model, and combining a permeability evolution rule determined by a triaxial seepage test; the optimum effect was determined to be achieved with three levels of loading, 12.80J, 20.3J and 27.25J respectively.

In order to better realize the invention, the method can further comprise the fifth step of designing three small explosive packages in each blast hole, filling the explosive packages at intervals by air, wherein the interval distance is greater than the sympathetic detonation distance of the explosive, and detonating at the micro-difference intervals; and (4) accurately delaying and detonating between blast holes.

compared with the prior art, the invention has the beneficial effects that:

1. The method is based on the indoor rock mechanical test, combines rock damage mechanical analysis and determines blasting parameters, has stronger pertinence, can effectively reduce the frequency of field explosion test, saves cost and time, avoids accidental errors of the field test, and has higher accuracy;

2. According to the invention, the average permeability increase of blasting is controlled by 2 times in a fine manner, so that the ore leaching time is theoretically shortened by half, meanwhile, the mechanical strength of a rock body is reduced by 2-3 MPa, the stability of the ore body can be ensured, and other blasting hazards such as blasting vibration, flying stones and the like can be strictly controlled by three-section delay blasting design in a small-dosage hole;

3. The invention provides a method for guiding on-site fine control of blasting infiltration in a laboratory, and the method can be widely popularized and applied and solves the problem of blasting infiltration in other projects.

Drawings

FIG. 1 is a flow chart of the small-dosage air interval blasting permeation-increasing method for the ionic rare earth ore.

FIG. 2 is a diagram of a portion of a rock sample and its composition according to the present invention.

FIG. 3 is a schematic diagram of the blasting infiltration enhancement of the present invention.

FIG. 4 is a comparison of NMR transverse relaxation time spectra before and after impact.

FIG. 5 is a comparison of before and after impact for MRI according to the present invention.

FIG. 6 is an evolution diagram of three kinds of incident energy constant amplitude impact damage of the present invention.

FIG. 7 is a diagram of the evolution of the four-stage loading lesion of the present invention.

FIG. 8 is a graph of the evolution of the porosity and permeability of the rock before and after impact according to the invention.

Fig. 9 is a view showing an essential structure in the blast hole of the present invention.

the meaning of the reference symbols in the figures: 1: stemming, 2: medicine package, 3: an air baffle.

Detailed Description

Reference herein to an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

the technical solutions in the embodiments of the present invention are described in detail below with reference to the drawings in the embodiments of the present invention so that the advantages and features of the present invention can be more easily understood by those skilled in the art, but the embodiments of the present invention are not limited thereto. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of protection of the present invention.

As shown in figure 1, the small-dosage air interval blasting permeation-increasing method for the ionic rare earth ore comprises the following specific steps:

the method comprises the following steps: collecting and preparing rock samples of a weathered layer ore deposit in a blasting area, excavating two to three rough blanks at different points in a rare earth weathered layer, wherein the size of the rough blanks is about 1m multiplied by 0.5m, fastening the ore samples by bamboo chips and steel wires along the periphery, undercutting the bottom of the ore samples, inserting wood boards into the bottom of the ore samples, taking out a plurality of rough blanks of the ore samples, properly protecting and transporting the rough blanks to a laboratory, and processing the rough blanks into standard cylindrical rock samples of 50mm multiplied by 100mm (diameter multiplied by height), 50mm multiplied by 50mm (diameter multiplied by height) and 50mm multiplied by 25mm (diameter multiplied by height) in the laboratory;

as shown in fig. 3, the sampled mineral deposit is located in the semiweathered layer of the rare earth ore.

Step two: nuclear magnetic resonance scanning is carried out on the pore structure of the rock sample, and the effective porosity: dividing the samples with the porosity of less than 2%, 2% -3%, 3% -4%, 4% -5%, 5% -6%, 6% -7%, 7% -8% and more than 8% into 8 groups, removing rock samples with the porosity of less than 2% and more than 8%, determining the internal pore distribution and the structural composition of weathered rocks by adopting nuclear magnetic resonance transverse relaxation time spectrum and nuclear magnetic resonance imaging on the remaining 6 groups of rock samples, wherein 6 groups of rock samples are respectively numbered as L, M, N, O, P, Q, the same group of rock samples are added with numbers behind capital letters, such as L3, and part of rock samples are shown in FIG. 2;

step three: testing the uniaxial compressive strength of each group of rock samples, and testing the uniaxial compressive strength of rocks with different porosities, wherein the static load strength of the rock samples with the porosity of 2-8% is 22.9-55.23 MPa;

step four: performing impact tests on rock samples with different porosities on a split Hopkinson pressure bar test System (SHPB), wherein the impact tests mainly comprise single impact and multiple impacts, the single impact simulates damage and permeability evolution rules of rocks after explosion impact with different doses, the multiple impacts comprise constant-amplitude cyclic fracturing impact and four-stage loading impact, and the influence on the damage and permeability of the rocks under differential interval blasting impact is simulated;

Returning to the step 2 after single or multiple impacts, carrying out nondestructive quantification and image observation by using a nuclear magnetic resonance transverse relaxation time spectrum such as a graph 4 and nuclear magnetic resonance imaging such as a graph 5, and recording impact load modes applied by a large number of pores and macroscopic cracks which are not generated after the rock sample is impacted; and returning to the step three, the fact that the uniaxial compressive strength is reduced by 3MPa-4MPa after impact is reasonably measured, and the requirement on ore body stability can be met.

step five: establishing a double-parameter damage evolution model according to an experimental result, determining the size of an impact load generating effective permeability, converting explosive quantity according to an energy method and designing pore network parameters, wherein the effective incident energy determined by single impact is 9.85J-52.65J, and the borne impact load is 66.12-148.17 MPa. Under constant-amplitude impact, a damage evolution mathematical model is established according to damage variables and relative impact times defined by using the elastic modulus. The following were used:

wherein the content of the first and second substances,E₀The dynamic elastic modulus of the relatively compact rock sample with the effective porosity of less than or equal to 1 percent is taken as 53 GPa; e_eThe dynamic elastic modulus of each impact rock sample is GPa; n is the total times that the rock sample can bear repeated impact with the same impact load; n is the number of rock sample impact, and N/N is the relative cycle impact number; alpha and beta are constants to be measured. FIG. 6 is a damage evolution diagram of three pre-impact constant amplitude cyclic impacts of 66.12MPa (12.80J), 84.19MPa (20.3J) and 98.30MPa (27.25J), respectively, and it can be seen that the impact times borne by the rock sample are smaller as the incident energy is increased during the constant amplitude impact, the damage accumulation is increased progressively during the constant amplitude impact and is divided into an acceleration accumulation stage and a deceleration accumulation stage, when D is greater than D, the damage evolution diagram is obtained by performing the constant amplitude cyclic impacts of three pre-impact degrees of 66.12MPa (12.80J), 84.>At 0.4, the rock damage accumulation is increased rapidly until the rock damage accumulation is destroyed, the damage degree must be lower than 0.4 to ensure the stability of the ore body, and the number of sections must be reduced as much as possible to reduce the disturbance of blasting vibration to the ore body. The evolution model mainly discloses the dynamic characteristics of weathered rocks under the condition of explosive impact and determines critical damage reading. On the basis, the samples are completely crushed after the fourth impact and the damage accumulation changes are shown in figure 7 under four-stage loading of 66.12MPa (12.80J), 84.19MPa (20.3J), 98.30MPa (27.25J) and 121.21MPa (37.92J) respectively, and the damage degree is close to 0.4 after the third impact, so that the determination can be madeThe optimal proposal is 66.12MPa (12.80J), 84.19MPa (20.3J) and 98.30MPa (27.25J) respectively. The porosity and permeability coefficient of the rock before and after impact are measured respectively by combining the triaxial seepage test results shown in fig. 8, and the permeability is obviously increased, and the average permeability is increased by 2.31 times along with the initial porosity.

As shown in fig. 3, the blast hole depth is about to penetrate through the semi-weathered layer and is 1m higher than the bedrock, the weathered layer depth is different and is designed according to the field geological conditions, the hole diameter is 90mm, the charging structure in the hole is as shown in fig. 8, 3 explosive packages in the hole are detonated from the hole bottom to the hole opening in sequence according to the time of 0ms, 500ms and 1000ms respectively, the explosive packages are separated by air barriers, the separation distance is determined according to the sympathetic detonation distance of the selected explosive, a blast hole is generally arranged between the wells and is not distributed in the wells by taking the No. 2 rock emulsion explosive as an example, the separation distance is 1 m.

It should be understood that various changes and modifications can be made by those skilled in the art after reading the teachings of the present invention, and such equivalents also fall within the scope of the appended claims.