WO2025063965A1

WO2025063965A1 - Method using mining tailings to produce structural products and the structural products

Info

Publication number: WO2025063965A1
Application number: PCT/US2023/074619
Authority: WO
Inventors: Randall Stremmel
Original assignee: Elkhorn Capital Holdings LLC
Current assignee: Elkhorn Capital Holdings LLC
Priority date: 2023-09-19
Filing date: 2023-09-19
Publication date: 2025-03-27
Anticipated expiration: 2026-03-19

Abstract

Embodiments presented provide for a method of using mine tailings in an economically profitable and environmentally safe manner. In some embodiments, mine tailings are added to a variety of other components to form an admixture that is then cured to form a structural block for use in the construction industry.

Description

METHOD USING MINING TAILINGS TO PRODUCE STRUCTURAL PRODUCTS AND THE STRUCTURAL PRODUCTS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] None.

FIELD OF THE DISCLOSURE

[0002] Aspects of the disclosure relate to methods to produce useful construction materials for the construction industry. More specifically, aspects of the disclosure relate to a method to produce a building block or brick from tailings from an industrial process as well as the structural element itself.

BACKGROUND

[0003] The efficient use of waste streams generated by industrial processes helps industry on both economic level and environmental levels. Many industries have waste streams that, if better utilized, may be an additional revenue source. Many of these waste streams are deposited directly into landfills. As available landfill space declines, the overall cost of lar disposal increases. Industries that generate large volumes of waste, therefore, spend large amounts of money on operations that negatively impact the economic costs of the business. One such large volume waste generator is the mining industry. Waste streams that do not have the required ore needed to be extracted must be disposed of at great expense. There is a need to find a cost-efficient solution for the disposal of mining tailings in a safe and efficient manner.

[0004] While there are known commercial uses for waste, silicate, and particulate materials such as coal, combustion, fly ash, and bottom ash as substitute materials in the production of low-strength cementitious products, the use of mine tailings has not occurred. Other known methods include producing a stabilized cementitious building block that combines fly ash and bottom ash with gypsum, lime, and calcium carbonate. The admixture described above is formed into a block under compressive force, and the block is allowed to cure under ambient conditions without the application of external heat. [0005] Known conventional mixtures of materials that include fly ash and bottom ash produce blocks that range between 1 ,000 and 2,500 psi compressive strength in the ultimate form. While such compressive strength is good, there is a need for structural materials that have a wider range of compressive capabilities than these known products.

[0006] These prior art disclosures typically produce construction products that exhibit relatively low compressive strength that increased slowly with time to ultimate levels that are inadequate for the use of these products as high-strength building brick or block.

[0007] There is a need to provide a practical method for the manufacture of high- strength bonded building bricks and blocks comprised primarily of mine tailings and other waste streams, such as nonferrous mine tailings and quarry fines. Furthermore, there is a need for a method for the manufacture of high-strength, building block bricks, and blocks comprising a material that does not contain free silica.

[0008] There is a need to provide an apparatus and methods that may make such blocks in an easy and reproducible manner.

[0009] There is a further need to provide apparatus and methods that do not have the drawbacks discussed above, namely structural blocks or bricks that have low compressive strength and that do not effectively use mine tailings.

[0010] There is still a further need to reduce economic costs associated with operations and apparatus described above with conventional tools and to provide for efficient use of mine tailings.

SUMMARY [0011] So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized below, may be had by reference to embodiments, some of which are illustrated in the drawings. It is to be noted that the drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments without specific recitation. Accordingly, the following summary provides just a few aspects of the description and should not be used to limit the described embodiments to a single concept.

[0012] In one example embodiment, a method for producing a structural element is disclosed. The method may entail obtaining a quantity of mining tailings. The method may also entail obtaining a quantity of lime. The method may also comprise obtaining a quantity of lye. The method may also comprise obtaining a quantity of water. The method may also comprise mechanically mixing the quantity of mining tailings, the quantity of lime, the quantity of lye, and the quantity of water to achieve a mixture to start a geopolymerization process. The method may also comprise placing the mixture in a mold defining the structural element. The method may also comprise compressing the mixture in the mold. The method may also comprise curing the mixture in the mold. The method may also comprise removing the mold.

[0013] In another example embodiment, a structural element is disclosed. The structural element may comprise a matrix of solid materials configured to withstand a structural load, the matrix of solid materials comprising approximately 37 weight percent of quartz. The matrix may also comprise approximately 12 weight percent of K-feldspar. The matrix may also comprise approximately 15 weight percent of mica. The matrix may also comprise approximately 4 weight percent of tobermorite. The matrix may also comprise a remainder of other materials. [0014] In another example embodiment of the disclosure, a method for producing a structural element is disclosed. The method may comprise obtaining a quantity of mining tailings. The method may also comprise obtaining a quantity of lime. The method may also comprise obtaining a quantity of lye. The method may also comprise obtaining a quantity of water. The method may also comprise mechanically mixing the quantity of mining tailings, the quantity of lime, the quantity of lye; and the quantity of water, to achieve a mixture to start a geopolymerization process. The method may also comprise curing the mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0016] FIG. 1 is a method for constructing a structural element that contains mining tailings.

[0017] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures (“FIGS”). It is contemplated that elements disclosed in one embodiment may be beneficially utilized in other embodiments without specific recitation. DETAILED DESCRIPTION

[0018] In the following, reference is made to embodiments of the disclosure. It should be understood, however, that the disclosure is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the disclosure. Furthermore, although embodiments of the disclosure may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting the disclosure. Thus, the following aspects, features, embodiments, and advantages are merely illustrative and are not considered elements or limitations of the claims except where explicitly recited in a claim. Likewise, reference to “the disclosure” shall not be construed as a generalization of the inventive subject matter disclosed herein and should not be considered to be an element or limitation of the claims except where explicitly recited in a claim.

[0019] Although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer, or section from another region, layer, or section. Terms such as “first,” “second,” and other numerical terms, when used herein, do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer, or section discussed herein could be termed a second element, component, region, layer, or section without departing from the teachings of the example embodiments.

[0020] When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected, coupled to the other element or layer, or interleaving elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no interleaving elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed terms.

[0021] Some embodiments will now be described with reference to the figures. Like elements in the various figures will be referenced with like numbers for consistency. In the following description, numerous details are set forth to provide an understanding of various embodiments and/or features. It will be understood, however, by those skilled in the art that some embodiments may be practiced without many of these details and that numerous variations or modifications from the described embodiments are possible. As used herein, the terms “above” and “below,” “up” and “down,” “upper” and “lower,” “upwardly” and “downwardly,” and other like terms indicating relative positions above or below a given point are used in this description to more clearly describe certain embodiments.

[0022] Aspects of the disclosure provide for a method for producing a structural element, such as a brick or block, to be used, for example, in building/construction projects. Aspects of the disclosure also include the structural elements themselves. In embodiments, mine tailings are received from a mining facility. In some embodiments, the tailings are large and inappropriately sized to be included in a structural block. The tailings, in this instance, may be crushed or reduced in size for allowance of incorporation of the tailings into a structural block or brick. In other instances, the tailings may be of sufficiently small size that any processing of reducing the size of the tailings is unnecessary. The mine tailings are then mixed with a quantity of lime, lye, and water. Mixing mining tailings material with a quantity of lime, lye, and water in a high-intensity mixer, followed by compaction and curing in an autoclave, leads to forming a construction material defined herein as a geopolymer.

[0023] Embodiments of the disclosure provide for combining different materials together for preparing a structural element. The structural element may be a structural block, a structural brick, a beam, or other structural element used in construction. Embodiments of the disclosure may also provide for creating structural elements for use with roadways, highway overpass construction, or other needed structural material.

[0024] In one non-limiting embodiment, mining tailings are combined with a quantity of lime, lye, and water. These materials are provided to a high-intensity mixer to facilitate chemical reactions between the ingredients. In embodiments, lime (calcium hydroxide) and lye (sodium hydroxide) act as activators for the geopolymerization process. In other embodiments, lye is omitted, thus the combination of materials includes mining tailings, lime and water.

[0025] After mixing, a process of compaction is performed. The compaction can be performed by transfer of the mixture to a molded shape. As will be understood, any type of molded shape may be used. Compaction may be achieved in pressures ranging from 5,000 to 10,000 pounds per square inch. Compaction helps in densifying the material and improving the overall strength of the final product.

[0026] After compaction, the product is cured. In embodiments, an autoclave curing is performed. The product undergoes curing at elevated temperatures between 190 degrees C to 210 degrees C (374 degrees F to 410 degrees F). The autoclave provides a controlled environment with increased pressure, typically 220 to 260 pounds per square inch. Curing in this manner allows for the geopolymerization process to progress more rapidly. Other types of environmental constraints may be used during the curing process. Control of humidity within the autoclave may be performed. [0027] The result of the end-product of geopolymerization produces a strong structural product. The geopolymerization process involves the formation of a three-dimensional network of inorganic polymers. This network is formed by the reaction between the aluminate and silicate species in the mining tailings material and the alkaline activators (lime and lye). Autoclave curing enhances the strength development of the geopolymer matrix.

[0028] Compaction and autoclave curing promotes strength development in the geopolymer material. The elevated temperatures and pressures during autoclave curing help accelerate the geopolymerization reaction and contribute to forming a solid and durable material.

[0029] In the aspects described, the geopolymerization process binds and encapsulates the mining tailings material, stabilizing the material. This reduces the environmental impact of the tailings by preventing the release of potentially harmful elements into the surrounding environment.

[0030] By incorporating mining tailings into the geopolymerization process, the method offers a potential way to repurpose waste materials and reduce the need for conventional construction materials such as brick, block, and aggregate.

[0031] During preliminary characterizations, it was noted some materials used contained approximately 1 percent pyrite. Some concern was expressed if this pyrite might oxidize during curing of the mixes, leading to deficient properties in the finished products. Testing found no degradation in the products produced under normal curing conditions. To confirm these results, it was decided to expose small samples of the cured mixes to a very aggressive “oxidation” test.

Test Procedure

[0032] The test procedure consisted of subjecting three small scale samples to three days at 200 degrees C in saturated steam, followed by 3 days drying at 70 degrees C. [0033] This regime was carried out for three full cycles. The samples after testing did not appear to be visually changed.

[0034] Note that there is a small reduction in water absorption with the test samples; however, a significant reduction in compressive strength.

[0035] The mineralogy of the test samples was determined, and the results compared to an untested sample is found in Table 1 .

Minerology of Embodiment

Table 1

[0036] The specific characteristics of the resulting geopolymer material, such as compressive strength, density, porosity, and durability, would depend on the composition of the mining tailings, the activator mix, the curing conditions, and the overall process parameters. [0037] According to the above, it is significant to note that amounts of calcite and tobermorite increase, while pyrite remains unchanged, and the amorphous content is reduced.

[0038] An oxidation test protocol was established in order to test resultant samples of materials from the methodologies described above. This oxidation test protocol was designed to be very aggressive, forcing mineralogical changes in the samples. It was anticipated that these forced mineralogical changes may not be experienced during the lifecycle of an average structural block or brick made by the process described. To enhance this oxidation test, the testing was performed on small samples that are less than 2 percent of the mass of the full-size bricks. This was designed to make sure that any possible changes could be identified and noted.

[0039] The oxidation test protocol may identify materials, such as pyrite for analysis. Pyrite, when exposed to water and certain conditions, may be detrimental to the lifecycle of the structural element. Surprisingly, in testing, the amounts of pyrite within the structural element do not affect the overall capability of the structural element. It is noted that there is apparently excess hydrated lime Ca(OH)2 in the mix that resulted in a small increase in tobermorite amounts and a large increase in the calcite in the test samples. Since the amorphous content was reduced in testing, it is assumed this is the source of the calcium entering in the above reactions.

[0040] The conversion of Ca(OH)2 to CaCCh is an expansive conversion. (2.2 to 2.7 g/cc); therefore, there is a concern related to microcracking of the cured matrix. The microcracking may lead, ultimately, to a loss in strength.

[0041] At the same time, CaCCh acted as a non-binding filler and thus plugged the generated cracks and reduced, or at least did not greatly affect, the water absorption properties of the test samples compared to the reference materials. [0042] In conclusion, the oxidation testing did not show that the contained pyrite in the tailings were susceptible to oxidative conversion, even under severe test conditions. This may be the result of the pyrite being encapsulated during original curing and thus unaffected by subsequent conditions.

[0043] Through analysis of the testing, a small amount of amorphous Ca(OH)2 led to the formation of calcite (CaCCh), and to a lesser extent, tobermorite. Per the analysis, calcite is not a bonding mineral and thus does not add to the strength of the final product. The formation of the calcite; however, may have filled the cracks it generated thus making the final product weaker but essentially unaffected with regard to water absorption.

[0044] These results suggest the original mix is correct and stable under normal use conditions. The results noted in the oxidation study are to be considered anomalous to what is expected to be encountered in any real-world application with full size bricks.

Example Embodiments of Mixtures

[0045] In one embodiment, a large-scale mix test procedure was performed. In this embodiment the following constituent materials were used:

Constituent Dry Mixtures - Large Scale Mixture

[0046] The following materials were used in creating a large batch of a structural product:

50 pounds of mining tailings

6.72 pounds of high calcium hydrated lime

[0047] The above mining tailings and lime were mixed in a high intensity mixer for approximately 3 minutes. After mixing, approximately 7 pounds of previously cured, jaw crushed, coarse material was added and mixed with the above dry mix. Water (5.1 pounds) was then added to the resultant mix. The resultant mix was wet mixed for five to ten minutes until homogenous. [0048] A portion of wet mix, described above, (5.5 pounds) was measured and placed in a tooling press and pressed at 5,000 pounds per square inch. The resultant structural element was cured for approximately 12 hours (including heat up, and cooling time) with an autoclave at 200 degrees C with saturated steam. In embodiments, some structural elements also included a dye or pigment to make the final product resemble a fired clay brick.

Compressive Strength Testing

[0049] Compressive strength tests were accomplished on the final structural elements for the large-scale mix provided above. Compressive strength tests were performed regarding ASTM method C67. Broken samples of the cured structural elements were sent for testing to try to extract heavy metals per TCLP methods (EPA 6010C and 7470A). As a result of the heavy metal test, the only detectable metal found was .36 mg/L barium. (For note, the maximum limit for barium extraction is 100 mg/L). Tests for arsenic, cadmium, chromium, lead, selenium, and silver did not produce any measurable results.

[0050] Compressive strength tests ranged from 7,870 pounds per square inch to 9,010 pounds per square inch.

Water Absorption Tests

[0051] Samples from the large-scale mix test, described above, were also tested for water absorption. As will be known, conventional made bricks (such as from fly ash), show significant susceptibility to water absorption. According to the testing results for aspects of the current disclosure, for a one-hour test, an amount of water absorption of 6.0 lbs. /ft³ and water absorption rate percentage of 4.8 percent was indicated. For a 24-hour test, the amount of water absorbed was 14.1 lbs./ft³ with an absorption percentage of 11.1 percent. Such water absorption tests indicate an excellent result where results for a one- hour test of 3 percent may be classified as “vitrified”. As a result, the test batches outperform even high grade “first class” masonry materials, commonly used with typical absorption percentages of 15 percent. Thus, the tests conclude that structural elements from the batches would pass ASTM C73-17 for severe weather application types of materials. Such advances using mining tailings easily outperform fly ash based structural products commonly known.

[0052] Another example embodiment of the disclosure is presented below. In this embodiment, material was characterized to determine the constituents. Dried material was dry screeded using 50, 70 and 100 mesh screens. The results are presented below in Table 2:

Amounts Passing Mesh Sizes

Table 2

[0053] In embodiments, the minus 100 mesh material was analyzed on a Microtrac Laser Particle Size Analyzer.

Minerology of Head and Screen Fractions

Table 3

Small Scale Sample Preparation

[0054] In one embodiment, three sets of samples were prepared. All of these consisted of mine tailings mixed with lime and water addition. After lime and water additions, the resultant mixture was placed in a form and then pressed at 5,000 psi, 7,500 psi, 10,000 psi to form “green” compacts. The samples demonstrate the effect of pressing force on cured properties. A second set of samples were also prepared, one with a 75/25 mix of tailings and an ash lag for fine aggregate and a second set containing 95 percent tailings with 5 percent red pigment to demonstrate what, if any, impact a pigment addition may have on cured properties.

[0055] After intensive mixing, the mixes were pressed into a 1 ,25-inch diameter by 1 - inch-high cylinder using an indicated pressing force.

[0056] The pressed green samples were cured in a saturated steam autoclave for 8 hours at a temperature of 190 degrees C and 200 psi gauge pressure. Mineralogy of Cured Product

Table 4

Treatment Process per Sample

Table 5 Compressive Strength of Structural Element

Table 6

Absorption

Table 7

Additional Example Embodiments

[0057] Some example embodiments of the disclosure shall now be described. In a first example embodiment a configuration of 100 percent tailings was added with lime with 15 ml of water. The resulting materials were mixed and then pressed into a mold at 5000 pounds per square inch. Two samples of the above-identified mixture were tested for absorption at one hour and at 24 hours after curing. Compressive strength testing was also conducted on each of the two samples. [0058] In a second example embodiment, a mixture of 75 precent tailings were mixed with 25 percent Niles BA Lime with 15ml of water. The resulting materials were mixed and then pressed into a mold at 7500 pounds per square inch. Two samples of the aboveidentified mixture were tested for absorption at one hour and at 24 hours after curing. Compressive strength testing was also conducted on each of the two samples.

[0059] In a third example embodiment, a mixture of 100 precent tailings was mixed with lime with 15 ml of water. The resulting materials were mixed and then pressed into a mold at 7500 pounds per square inch. Two samples of the above-identified mixture were tested for absorption at one hour and at 24 hours after curing. Compressive strength testing was also conducted on each of the two samples.

[0060] In a fourth example embodiment, a mixture of 100 percent tailings was mixed with lime with 15 ml of water. The resulting materials were mixed and then pressed into a mold at 7500 pounds per square inch. Two samples of the above-identified mixture were tested for absorption at one hour and at 24 hours after curing. Compressive strength testing was also conducted on each of the two samples.

[0061] Results for the first through fourth examples embodiments are described in the next two tables (Table 8 and Table 9). All formations are created without an addition of lye.

Table 8

Table 9

[0062] Other examples are provided. Example 5 provides 100 percent tailings mixed with a 15ml lime solution and pressed at 5000 pounds per square inch.

[0063] Example 6 provides 100 percent tailings with red pigment and with a 15ml lime solution and pressed at 5000 pounds per square inch.

[0064] Example 7 provides 75 percent tailings with 25 percent other materials (Niles BA) with a 15 ml lime solution and pressed at 5000 pounds per square inch.

[0065] Example 8 provides 100 percent tailings mixed with a 15m I lime solution and pressed at 7500 pounds per square inch.

[0066] Example 9 provides 100 percent tailings mixed with a 15m I lime solution and pressed at 10000 pounds per square inch.

Table 10

[0067] Compressive strength stressing for Examples 5 to 9 are presented below in Table 11.

Table 11

[0068] Other embodiments of the disclosure provide the addition of lye to the overall mixture, thus configurations of structural elements may incorporate lye while others may not. Examples of structural elements including lye follow. Example 10 provides for a mixture with an 8 molar content of lye and 12 percent lime. Example 10 was tested for absorption showing a very low percentage of absorption (under 2.73 percent), as provided in Table 12.

Table 12 [0069] Compressive tests were conducted on Example 10. For the forming pressure of 5800 pounds per square inch, compressive tests resulted in greater than 5000 pounds per square inch.

Table 13

[0070] Additional examples (Examples 11 , 12) are also described. Example 11 is a mixture that includes a 6 molar amount of lye. Example 12 is a mixture that contains an 8 molar amount of lye. Absorption tests show that percentage absorption of 2.15 percent or less.

Table 14

[0071] Compression tests for examples 11 and 12 are also described. With a compression of 5000 psi into a mold and subsequent curing, the minimum amount compressive strength was 4700 psi. For example 12, compressive strengths shown an exception value of 8500 psi or greater.

Table 15

[0072] The results presented above demonstrate the final products that can be produced from mining tailings. Compressive strengths, illustrated above, are exceptional and in most cases exceed the capacity of most testing machines. Neither of the additives tested (fine bottom slag or commercial red pigment) improved performance.

[0073] According to the above identified results, the samples produced with the 10,000 psi meet the severe weather, water absorption requirements. All samples produced meet the moderate weather rating. It is noted that the absorption results of the small-scale products generally have a higher absorption rate than full size product results. This is achieved because of a higher specific surface area of the smaller samples in comparison to a full-size sample. Full size water absorption testing listed for the full-size products provide more consistent and reliable results.

[0074] Referring to FIG. 1 , a method 100 for producing a structural element is illustrated. The method 100 may be used to make a structural brick, a structural block, or complex structural shape. The sizes of the shapes may be increased or decreased according to the needs of an engineer. At 102 mining tailings are obtained. As discussed above, the mining tailings may be sized, as needed. To size the mining tailing, the tailings may be crushed by mechanical equipment. At 104, lime is added to the mixture of tailings to produce a first mixture. At 106, lye is added to the first mixture to produce a second mixture. At 108, water is added to the second mixture to make a third mixture. As will be understood, the lime, lye and water may be added in different orders, thus water may be added at 104, lye at 108, and lime at 106. Other possibilities exist, therefore the method shown is but one possible alternative. The third mixture is then mechanically mixed, at 110, for a period of time. The period of time for mixture may depend upon the volumes of material incorporated into the mixer. A high-speed mixer may be used to create a homogenous final mixture. During the mixing, the lime (calcium hydroxide) and lye (sodium hydroxide) act as activators to start a geopolymerization process.

[0075] After mixing at 110, a portion of the homogenous final mixture is placed into a mold at 112. The mold delineates the shape of the anticipated final product. At 114, a compaction process is performed on the homogenous final mixture placed in the mold. The compaction may be 5,000 psi, 7,500 psi or 10,000 psi in some non-limiting embodiments. The compaction may be performed by a hydraulic press. After compaction, the mold with contents is placed into an autoclave and then removed from the autoclave and dried. In one example embodiment, the structural element is dried in the autoclave for three days at 200 degrees C in a saturated steam environment followed by three days of drying at 70 degrees C. At 118, the structural element may be removed from the mold.

[0076] In embodiments, a pigment may be added prior to mixing at 110. Such pigments may be added to increase the architectural look of the final product. Amounts of tailings, water, dye, lye, and lime may be according to any of the previously described amounts. In some embodiments, materials may be dried without being put in a mold and then subsequently crushed. The crushed material may be used as an aggregate in construction purposes. In some embodiments, different types of presses may be used when materials are placed into a mold. Such presses may include a rolling press as a non-limiting embodiment. In some embodiments other materials may be added such as lye or a pigment. Other weight percentages may be used compared to the above stated amounts. [0077] Example embodiments of the claims are presented. The scope of the aspects described should not be considered limiting. In one example embodiment, a method for producing a structural element is disclosed. The method may entail obtaining a quantity of mining tailings. The method may also entail obtaining a quantity of lime. The method may also comprise obtaining a quantity of lye. The method may also comprise obtaining a quantity of water. The method may also comprise mechanically mixing the quantity of mining tailings, the quantity of lime and the quantity of water, to achieve a mixture to start a geopolymerization process. The method may also comprise placing the mixture in a mold defining the structural element. The method may also comprise compressing the mixture in the mold. The method may also comprise curing the mixture in the mold. The method may also comprise removing the mold.

[0078] In another example embodiment, the method may be performed wherein the structural element is one of a structural brick, a structural block, and a complex structural shape.

[0079] In another example embodiment, the method may be performed wherein the compressing the mixture is at approximately 5,000 psi.

[0080] In another example embodiment, the method may be performed wherein the compressing the mixture is at approximately 7,500 psi.

[0081] In another example embodiment, the method may be performed wherein the compressing the mixture is at approximately 10,000 psi.

[0082] In another example embodiment, the method may be performed wherein the mechanical mixing is performed by a high-speed mixer.

[0083] In another example embodiment, the method may be performed wherein the curing the mixture in the mold further comprises placing the mixture in the mold in an autoclave for a period of time and then drying the mixture in the mold for a drying time. [0084] In another example embodiment, the method may be performed wherein the autoclave is at 200 degrees C and the period of time is three days.

[0085] In another example embodiment, the method may be performed wherein the drying time is three days and a drying temperature is 70 degrees C.

[0086] In another example embodiment, the method may be performed wherein the compressing the mixture in the mold is performed by a hydraulic press.

[0087] In another example embodiment, a structural element is disclosed. The structural element may comprise a matrix of solid materials configured to withstand a structural load, the matrix of solid materials comprising approximately 37 weight percent of quartz. The matrix may also include approximately 12 weight percent of K-feldspar. The matrix may also include approximately 15 weight percent of mica. The matrix may also include approximately 4 weight percent of tobermorite. The matrix may also include a remainder of other materials.

[0088] In another example embodiment, the structural element may be configured wherein at least a portion of the remainder of the other materials includes at least 1 percent kaolinite.

[0089] In another example embodiment, the structural element may be configured wherein at least a portion of the remainder of the other materials includes at least 1 percent pyrite.

[0090] In another example embodiment, the structural element may be configured wherein at least a portion of the remainder of the other materials includes at least 25 percent amorphous material. [0091] In another example embodiment of the disclosure, a method for producing a structural element is disclosed. The method may comprise obtaining a quantity of mining tailings. The method may also comprise obtaining a quantity of lime. The method may also comprise obtaining a quantity of lye. The method may also comprise obtaining a quantity of water. The method may also comprise mechanically mixing the quantity of mining tailings, the quantity of lime, the quantity of lye; and the quantity of water, to achieve a mixture to start a geopolymerization process. The method may also comprise curing the mixture.

[0092] In another example embodiment, the method may further comprise crushing the cured mixture.

[0093] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

[0094] While embodiments have been described herein, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments are envisioned that do not depart from the inventive scope. Accordingly, the scope of the present claims or any subsequent claims shall not be unduly limited by the description of the embodiments described herein.

Claims

CLAIMS What is claimed is:

1 . A method for producing a structural element, comprising: obtaining a quantity of mining tailings; obtaining a quantity of lime; obtaining a quantity of water; mechanically mixing the quantity of mining tailings, the quantity of lime, and the quantity of water, to achieve a mixture to start a geopolymerization process; placing the mixture in a mold defining the structural element; compressing the mixture in the mold; curing the mixture in the mold; and removing the mold.

2. The method according to claim 1 , wherein the structural element is one of a structural brick, a structural block, and a complex structural shape.

3. The method according to claim 1 , wherein the compressing the mixture is at approximately 5,000 psi.

4. The method according to claim 1 , wherein the compressing the mixture is at approximately 7,500 psi.

5. The method according to claim 1 , wherein the compressing the mixture is at approximately 10,000 psi.

6. The method according to claim 1 , wherein the mechanical mixing is performed by a high-speed mixer.

7. The method according to claim 1 , wherein the curing the mixture in the mold further comprises placing the mixture in the mold in an autoclave for a period of time and then drying the mixture in the mold for a drying time.

8. The method according to claim 7, wherein the autoclave is at approximately 200 degrees C and the period of time is three days.

9. The method according to claim 8, wherein the drying time is three days, and a drying temperature is 70 degrees C.

10. The method according to claim 1 , wherein the compressing the mixture in the mold is performed by a hydraulic press.

11 . The method according to claim 1 , wherein the compressing the mixture in the mold is performed by a rolling press.

12. A structural element, comprising: a matrix of solid materials configured to withstand a structural load, the matrix of solid materials comprising: approximately 37 weight percent of quartz; approximately 12 weight percent of K-feldspar; approximately 15 weight percent of mica; approximately 4 weight percent of tobermorite; and a remainder of other materials.

13. The structural element according to claim 12, wherein at least a portion of the remainder of the other materials includes at least 1 percent kaolinite.

14. The structural element according to claim 12, wherein at least a portion of the remainder of the other materials includes at least 1 percent pyrite.

15. The structural element according to claim 12, wherein at least a portion of the remainder of the other materials includes at least 25 percent amorphous material.

16. A method for producing a structural element, comprising: obtaining a quantity of mining tailings; obtaining a quantity of lime; obtaining a quantity of lye; obtaining a quantity of water; mechanically mixing the quantity of mining tailings, the quantity of lime, the quantity of lye; and the quantity of water, to achieve a mixture to start a geopolymerization process; and curing the mixture.

17. The method according to claim 16, further comprising: crushing the cured mixture.