A filled concrete product containing gangue materials as aggregate raw material

Abstract

The invention relates to a filled concrete product containing as aggregate gangue materials which are obtained during the extraction and / or processing of chromite mines, which do not contain mineralization, and which cannot be economically enriched.

Description

[0001] A FILLED CONCRETE PRODUCT CONTAINING GANGUE MATERIALS AS AGGREGATE RAW MATERIAL

[0002] TECHNICAL FIELD

[0003] The invention relates to a filled concrete product containing as aggregate gangue materials which are obtained during the extraction and / or processing of chromite mines, which do not contain mineralization, and which cannot be economically enriched.

[0004] PRIOR ART

[0005] Concrete is a material made by mixing cement, natural or artificial aggregate, water and, when necessary, chemical or mineral additives and gains strength with the hydration of cement. By mixing these components, a homogeneous mass is obtained. Then this mixture is poured into molds to take the desired shape and then left for a while to harden. After hardening, concrete becomes a building material with properties such as high strength, durability, and longevity.

[0006] Filling in mining is the process of partially or completely filling a space opened by production using hand, gravity, mechanical, pneumatic and hydraulic tools. The development and utilization of filling technology in the world has made great progress in the last two decades. The mining industry is particularly interested in this technology for filling large production open spaces underground. The concretes prepared for this purpose are called filled concrete. Filled concrete recipes generally consist of cement, aggregate, and water components. In filled concrete, the change is usually in the aggregate used.

[0007] Aggregates have two origins as natural aggregates and artificial aggregates according to the sources from which they are obtained. Artificial aggregates are crushed or unbroken aggregates that emerge as a by-product exposed to high temperatures as a result of industrial processing. These aggregates, which are industrial products, are blast furnace slag, fly ash aggregate, expanded perlite, and expanded clay artificial aggregates. Natural aggregates are obtained from natural sources such as creeks, streams, lakes, plains, sea beds, quarries or mines.

[0008] Chromium (Cr) is a metallic element that is hard and bluish in color. The mineral chromite is the only source of chromium known in the art. According to geologists, the world's exploitable chromite ore reserves are estimated at around 11 billion tons, enough to meet current demand for hundreds of years. It is mostly used in the production of stainless steel and other metal alloys.

[0009] During the extraction of chromite mine, materials called gangue emerge. Gangue material is defined as a substance or material that does not contain mineralization or cannot be enriched according to the current economic and technical conditions, but which is compulsory to be produced due to the operation and has not been subjected to any process other than excavation. Ferrochrome production facilities and marble quarries are among the leading mining branches where much material emerges as a waste. Quite large areas may be needed for the storage of material of this size. These sites are regularly monitored with analysis and activity reports in line with the provisions of the relevant legislation, and in case of expiration of the operating license, it is required by the relevant legislation that the transportation of the gangue materials is carried out within six months at the latest. When these are taken into consideration; keeping the gangue as waste occupies space in the mine site and may cause problems such as increasing costs when it needs to be replaced. In this respect, the utilization of gangue materials is an important resource in today's world where natural aggregates are becoming increasingly scarce.

[0010] In the relevant technical field, it is contemplated that the research and development of the use of gangue materials obtained during the production of chromium from chromite mines as raw materials in value-added products will meet the innovation criterion.

[0011] SUMMARY OF THE INVENTION

[0012] The inventors of the present invention propose that the gangue materials obtained from chromite mines should be investigated and developed as a reusable raw material. For this purpose, it aims to introduce technical teachings on the use thereof as aggregate, especially in filled concrete products. Accordingly, the primary object of the present invention is to introduce a filled concrete containing gangue materials that emerge during the enrichment or processing of chromite mines.

[0013] The other secondary object to be achieved with the realization of this is to ensure that these technical problems are avoided by including the gangue materials, which are difficult and costly to store, in a value-added product.

[0014] Another secondary object is to reduce the costs of filled concrete products by using gangue materials as aggregate.

[0015] BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 shows a representation of the values related to the strength of the filled concrete.

[0017] DETAILED DESCRIPTION OF THE INVENTION

[0018] In this detailed description, the invention relates to a filled concrete product containing as aggregate gangue materials which are obtained during the extraction and / or processing of chromite mines, which do not contain mineralization, and which cannot be economically enriched, and is described by way of non-limiting examples only for a better understanding of the subject matter.

[0019] In the relevant technical field, it is known that a material must contain certain components in order to be used as aggregate and to provide the expected technical properties to the final product filled concrete. The most important of these components are MgO, SiC>2, and AI2O3 components. It is also clear that they must be in certain weight ratios. Therefore, it is necessary to research whether the raw materials to be used as aggregates contain these components. Technical teachings regarding why these components are included in the raw materials to be used as aggregates are known by experts in the art. For this reason, the technical solutions and advantages of said components as aggregate are not mentioned.

[0020] Accordingly, the inventors of the present invention propose the use of gangue materials which are obtained during the production of chrome ores from chromite mines, which do not contain mineralization, and which cannot be economically enriched as aggregate for filled concretes.

[0021] The inventors of the present invention have attempted to prove the technical properties of the gangue materials obtained from chromite mines and their usability as aggregate with some tests for the relevant technical field.

[0022] Firstly, elemental analysis is carried out as in Table 1 to determine the suitability of using the gangue materials as aggregate material.

[0023] Table 1. Elemental analysis of sample gangue material of the invention.

[0024] It comprises SiC>2 at a value in the range of 30% to 40% by weight, MgO at a value in the range of 30% to 45% by weight for its use as an aggregate material in the filled concrete product of the invention. With these values it contains, its use as an aggregate material of the filling product of the present invention is proven by tests.

[0025] One of the technical problems encountered in the prior art is the expansion issue. Table 2 shows the results of the Alkali-Silica Reaction (ASR) experiment. Table 2 shows the average expansion values of the experimental samples when they were kept in 80 °C, 1 M NaOH solution for 14 days. The thermal expansion of the samples arising from the temperature difference between 20 °C and 80 °C is reduced. Since the expansion value obtained in 14 days for mortar bars produced in accordance with the standard with fine aggregate and CEM II 42.5 bulk cement used in the test is less than the 0.10% limit values recommended for ASTM C1260 Test Method, it is seen that there is no potential expansion problem in the fine aggregate-cement mixture used in these experiments for the current test conditions. This result shows that the gangue material is suitable for use as an aggregate.

[0026] Table 2. Alkali-Silica Reaction (ASR) test results of gangue materials of the invention.

[0027] TESTS

[0028] In order to examine the suitability of the gangue material as an aggregate, water absorption and porosity tests for fine aggregate (0-4 mm) in Table 3 and coarse aggregate (4-50 mm) in Table 4 are included.

[0029] In order to obtain the data in Table 3, the studies detailed in the following lines are carried out. TS EN 1097-6, AASHTO T84, ASTMC 128 standards were used in fine aggregate water absorption and porosity tests. The process steps of the experiment in Table 3 are as follows:

[0030] - 1000 g test sample is prepared.

[0031] - Enough water is added to cover the sample in the tray.

[0032] It is soaked in water for 24 hours. Excess water is drained from the tray.

[0033] - The samples become saturated surface-dry (SSD) by hot air source. Weighing is done in this state and the SSD weight is obtained. Said SSD is determined by the cone method.

[0034] - The cone is pressed into the mold in 3 layers of 25 strokes each time. It is turned upside down. The pile is divided in half with a fine-section trowel.

[0035] - If the sample stays firm, drying is continued. If the sample slumps, the state of SSD is achieved.

[0036] Calculations used during experimental studies:

[0037] • The empty weight of the pycnometer is determined. A=MP

[0038] • Water is added up to the pycnometer line and its weight is determined. B=MP+S

[0039] • Samples are placed in a pycnometer and weighed. C=MP+A

[0040] • Water is added to the sample and weighed. D=MP+A+S • The sample is taken to the tray, dried at 110 °C, and weighed. E=Mdry ,

[0041] (C- J-F

[0042] Water Absorption= *100

[0043] The water absorption test results for fine aggregate (1-4 mm) of the gangue material using the expressed test processes and calculations are given in Table 3.

[0044] Table 3. Water absorption and porosity test values of (1-4 mm) size gangue materials.

[0045] In order to obtain the data in Table 4, the studies detailed in the following lines are carried out. TS EN 1097-6, AASHTO T85, ASTMC 128 standards were used in fine aggregate water absorption and porosity tests. The process steps of the experiment in Table 4 are as follows:

[0046] - 1000 g test sample is prepared.

[0047] - The sample in the tray is soaked under water until it overflows for 24 hours.

[0048] - Samples removed from the water achieve SSD state with air.

[0049] - Weighing is done and the SSD weight is obtained. (MSSD)

[0050] - The samples are immersed in a bucket filled with water with a wire basket with - It is dried in an oven at 110 °C. (Mdry)

[0051] Calculations used during experimental studies:

[0052] The water absorption test results for coarse aggregate (4-50 mm) of the gangue material using the expressed test processes and calculations are given in Table 4.

[0053] The water absorption capacity of the aggregate is crucial for the mixture calculations of the material. In addition, the water absorption capacity of the aggregate is of great importance for the durability of the concrete. In aggregates with high water absorption capacity, water can easily enter the pores, and the water filling the pores in cold weather can freeze, thereby expanding and causing cracks.

[0054] Table 4. Water absorption and porosity test values of (4-50 mm) size gangue materials.

[0055] The water absorption capacity of the aggregate is crucial for the mixture calculations of the material. In addition, the water absorption capacity of the aggregate is of great importance for the durability of the concrete. In aggregates with high water absorption capacity, water can easily enter the pores, and the water filling the pores in cold weather can freeze, thereby expanding and causing cracks. The conducted water absorption and porosity tests show that the gangue material is suitable for use as an aggregate in filled concrete.

[0056] Methylene blue test is performed on the gangue material of the invention. The main purpose of this experiment is to determine the amount of clay and silt in the aggregate mixture. Because the excess of undesirable structures such as clay and silt in the aggregate causes the effect of reducing the strength of the concrete. Clay and silt are materials that absorb methylene blue. If the amount of clay and silt in the mixture is higher, the amount of methylene blue used is higher. As a result of the experiments conducted, it is shown that gangue is suitable for use as an aggregate and that there are no undesirable structures such as clay and slit.

[0057] The distribution of the grains in the aggregate pile according to their size is called gradation (granulometry). As can be seen from the gradation curves given in the figure, it is observed that the gradation curves of the samples are close to the thickness limit. The desired gradation curve in filled concrete is desired to be between the ideal and the thickness limit. Because it is observed that the desired strength values from the filled concrete used in the areas exposed to load are achieved in the samples with gradation in these ranges. The gradation curves obtained at this stage appear to be suitable for experiments carried out under process conditions.

[0058] The values given in Fig. 1 show the strength of the filled concretes obtained. Compressive strength of concrete is the highest mechanical strength resistance of concrete in order not to break under the influence of axial load. The most researched issue in concrete is the compressive strength of concrete. What is crucial for concrete is the relationship between compressive strength and stress-deformation under pressure. The compressive strength of concrete is a function that changes over time and takes its final strength after years. Considering the strength values expected from the filled concrete, the upper and lower limits of uniaxial compressive strength value are achieved as a value of 3 MPa-5 MPa for 7 days, 5 MPa-10 MPa for 14 days and 6 MPa-12 MPa for 28 days. With these values, it is determined that the gangue material used as aggregates are suitable for use as aggregates in filled concrete due to their uniaxial strength properties being within acceptable limits and even more. Thus, in these experimental studies, it is seen that strength expected from filled concrete is provided. The filled concrete product of the invention contains as aggregate gangue materials at a value in the range of 55% to 90% by weight, which are obtained during the production of chrome ores from chromite mines, which do not contain mineralization, and which cannot be economically enriched. The reason for selecting these values is to ensure that the final product has the desired strength and ease of application properties, while also maintaining cost-effectiveness.

[0059] The scope of protection of the invention is specified in the appended claims and cannot be limited to what is described for illustrative purposes in this detailed description. It is clear that a person skilled in the art can produce similar embodiments in the light of what is explained above, without deviating from the main theme of the invention.

Claims

CLAIMS1. A filled concrete product containing as aggregate gangue materials which are obtained during the extraction and / or processing of chromite mines, which do not contain mineralization, and which cannot be economically enriched.

2. A filled concrete product according to claim 1 , characterized in that it contains as aggregate gangue materials at a value in the range of 55% to 90% by weight, which are obtained during the production of chrome ores from chromite mines, which do not contain mineralization, and which cannot be economically enriched.

3. A filled concrete product according to one of the preceding claims, characterized in that said gangue materials, which are obtained during the production of chrome ores from chromite mines, which do not contain mineralization, and which cannot be economically enriched, contain SiC>2 at a value in the range of 30% to 40% by weight, and MgO at a value in the range of 30% to 45% by weight.

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