Magnesite Mine Research Articles

Magnesite Mine Waste as a Sustainable Binder for Low-Fines Self-Compacting Concrete: Engineering Property and Ecological Impact

<p>Mine waste management has become a global concern due to its environmental and health impacts, as well as the high cost of disposal. Recent advancements focus on recycling mine waste into resources using effective conservation methods and waste management systems. The building sector, a major consumer of natural resources, has seen studies on using waste materials in concrete. This study examined the feasibility of replacing cement with mine waste in two phases - binary blend (cement + mine waste) and ternary blend (cement + fly ash + mine waste) at 10%, 20%, and 30% doses. The study evaluated fresh properties like slump flow, T50 slump, V-funnel, J-ring, and L-box, and hardened properties like compressive, splitting tensile, and flexural strengths. It also investigated microstructural characteristics, cost, energy impact, and CO2 emissions. The results showed good performance in fresh characteristics for almost all mixtures but failure in hardened properties. The achieved strength was backed by microstructural analysis. Binary blended SCC reduced costs by 5%, energy by 25%, and CO2 emissions by 28%, while ternary blended SCC cut costs by 8%, energy by 32%, and CO2 emissions by 36%.</p>

Sustainable use of magnesite mine waste in self-compacting concrete and its study on strength, microstructure, cost and CO2 emission

Managing waste materials from mining is of universal interest owing to its massive volume, ecological impacts, health hazards, and disposal challenges despite high operational costs. Advancements advocate for recycling mine waste to sustainably support construction. As the construction sector heavily consumes resources, utilizing mine waste from magnesite mines (MMW) in concrete has gained attention. This experimental study assesses the viability of substituting MMW for natural fine and coarse aggregates in self-compacting concrete (SCC) at intervals of 10% up to 50% by weight. Evaluations were done on fresh (slump flow, T50 slump, V-funnel, J-ring, L-box) and hardened (compressive, splitting tensile, and flexural strength) properties, along with microstructural features, cost, and CO2 emissions. The findings unveil that nearly all mixtures exhibit commendable performance, where mine waste is replaced for fine and coarse aggregates showcasing superior fresh and hardened properties, respectively. Fresh property results reveal the SF1 flow category with VF1 and VF2 viscosity types for the SCC mixtures. Moreover, these SCC mixtures observed substantial strength enhancements of approximately 10% to 15% in compressive, splitting tensile and flexural test results at 28 and 90 days. Microstructural analysis corroborates the observed strength outcomes, indicating a denser concrete matrix. Significant environmental and economic benefits were observed, including a notable 20% reduction in CO2 emissions and 17% cost savings. These findings underscore the potential of integrating MMW into SCC mixtures as a sustainable approach towards construction materials, offering both performance and environmental advantages.

Heavy metal accumulation in root and shoot tapioca plant biomass grown in agriculture land situated around the magnesite mine tailings

Heavy metal pollution in soil has emerged as a major environmental concern. This can be attributed to human activities such as mining, modern agriculture, and industrialization. This study was conducted to determine how heavy metals spread from mine tailings to surrounding farmland. Metal absorption and accumulation were also investigated in the root and shoot biomass of tapioca crops grown in those farmlands. Metal concentrations in MTAS1 were 85.3 ± 1.2, 45.8 ± 1.5, 134.8 ± 1.7, 92.4 ± 2.2, and 78.95 ± 1.4 mg kg-1, respectively. Heavy metal concentrations in MTAS2 and MTAS3 were found to be 79.62 ± 1.6, 75.4 ± 1.5, 41.31 ± 1.1, 47.8 ± 1.6, 142.5 ± 2.1, 128.4 ± 1.4, 86.2 ± 1.9, 79.5 ± 1.3, and 83.4 ± 1.2 mg kg-1, respectively. Tapioca crop shoot and root biomass grown at these metal polluted sites absorbed and accumulated significant amounts of Cd, Cu, Zn, Pb, Ni, and Mn. Notably, the metal content of the tapioca crop's root and shoot biomass exceeded national standards.

Utilization of waste face masks to reinforce magnesite mine tailings for sustainable subgrade construction

The disposal of magnesite mine tailings (MMT), a by-product of magnesite mining, raises significant environmental concerns due to its adverse effects on soil, water and air quality. Likewise, the improper disposal of used face masks exacerbates environmental burdens. The innovative use of polypropylene fibres (PPF) derived from disposable face masks to reinforce. This study explores the compaction and strength characteristics of PPF-MMT composites with varying fibre content to develop a sustainable composite for subgrade construction. The findings indicate that the addition of PPF increases optimal moisture content and decreases maximum dry density. Shear strength analysis reveals a linear failure envelope for both MMT and PPF-MMT, with initial angle of internal friction improvement at lower PPF content (0.25% and 0.5%) but a decline at higher contents (0.75% and 1%). Importantly, PPF-MMT consistently exhibits a unique strain-hardening behaviour across all stress levels, distinguishing it from MMT, which only transitions to strain-hardening at higher stresses. Under vertical load, MMT shows contraction, while the PPF-MMT composite initially contracts but later dilates due to increased fibre-MMT interaction during horizontal displacement. Furthermore, California bearing ratio (CBR) tests demonstrate increased dry CBR with PPF, reaching a peak of 33.85% at 0.5% fibre content. The soaked CBR tests affirm the remarkable durability of PPF-MMT, maintaining significantly higher values than MMT even after 60 days of soaking. The study concludes that 0.5% fibre content as optimum dosage.

A reliability-based mechanical-empirical design method for flexible pavements containing cement-treated magnesite mine tailings as subgrade

The large-scale mining of magnesite generates substantial quantities of magnesite mine tailings (MMT), which pose a significant threat to soil, water, and air quality. Utilising cement-treated MMT as a subgrade material presents a promising solution to address this environmental challenge. However, the existing mechanical-empirical design methods cannot be directly employed due to the uncertainties associated with the various design parameters particularly the behaviour of cemented MMT. This research introduces a novel reliability-based MEM design method to design flexible pavements incorporating cemented MMT as subgrade. A three-layered flexible pavement configuration, with a middle granular layer sandwiched between the top bituminous layer and the bottom stabilised subgrade, was examined. The response surface model and finite element model were developed to determine the fatigue and rutting strains of the pavement. Monte Carlo simulation was adopted to compute reliability. Further, a sensitivity analysis was performed to probe the contribution of input parameters on the reliability of pavement. The developed methodology was illustrated with a case study. Reliability analysis revealed that the cemented MMT pavement achieved reliabilities of 97.44% and 96.27% for fatigue and rutting criteria, respectively, under a design traffic load of 30 million standard axles (msa). Additionally, the sensitivity analysis identified the modulus of elasticity of the granular layer and bituminous layer as the most critical input variables. Thus, the developed design methodology for pavements incorporating MMT enables the engineers to design MMT-based flexible pavements considering the uncertainties.

Bioremediation potential of biochar and metal tolerant Bacillus cereus on heavy metal polluted mine surrounding pond and assessed cytotoxicity and phytotoxicity attributes of treated water on Brine shrimp larvae and Paddy seedling

BackgroundThe soil has been polluted severely with metals leached from mine tailings. Thus, these mine tailings can also reduce the fertility of farmland nearby the mining activities. The research was performed to assess the physicochemical attributes of water sample collected from magnesite mine surrounding pond and evaluate the bioremediation potential of pre-characterized biochar and Bacillus cereus under various treatments set up in a laboratory condition. MethodsStandard acid digestion method was followed to quantify the metal content in the soil. In-vitro remediation method was performed to determine the remediation potential of biochar and B. cereus. In-vitro method was followed to find the toxicity on Artemia franciscana larvae and Orysa sativa. FindingsThe results shows that the heavy metal contents like As, Cd, Pb, Cr, Cu, Zn, Cl−, SO42−, as well as Hg beyond the permissible limit. The dissolved oxygen (DO) level was also notably poor. The bioremediation study with various treatment groups (BT1, BT2, BT3, and BT4) showed that the group BT2 (biochar + B. cereus) effectively reduced the heavy metals in the treated pond water under 10 days of exposure. Furthermore, the BT2 treated water sample alone showed no toxic effects on A. franciscana larvae and O. sativa.

Phytoremediation and genetic adaptation potential of Jatropha curcas on heavy metals enriched mine tailings

BackgroundPhytoremediation is aninexpensive green method that uses metal-tolerant plants to extract these contaminants and restore the soil. MethodsThe phytoremediation potential and genomic DNA/genetic adaptability nature of Jatropha curcas was investigated by 90 days of greenhouse experiment.The genomic DNA stability was determined through RAPD analysis. Soil characterization results the magnesite mine tailing physicochemical parameters (pH, Total carbon, Total hardness, NPK, Cr, Pb, Mn, and Cd) were beyond the acceptable limits. Thus, the mine soil diluted with fertile soil (group a-f) to create different treatment groups. Significant FindingsThe results stated that soil diluted with maximum quantity of fertile soil showed maximum growth and considerably extracted the metals from the soil compared to undiluted (group e) soil and other groups. The BAF and TF values strongly suggests that the J.curcas is suitable candidature with phytoextraction potential. The RAPD analysis on whole genomic DNA revealed that the plan possesses considerable metal adaptation potential under metal stress condition confirmed by GTS and DNA polymorphism analyses through RAPD and also TSP analyses. Hence, this J. curcas can be employed as considerable plant with phytoextraction (as hyperaccumulator) potential to remove the heavy metals from the soil.

Eco-efficiency evaluation of sustainable self-compacting concrete using magnesite mine waste

Utilization potential of industrial by-products/wastes as construction material requires adequate workability, strength and other required properties as specified by standard codes of practice and certain sustainability criteria. Coal combustion byproduct (fly ash) and mine waste are a few of the abundantly available wastes that create a challenging task in their disposal with the current practice of dumping on-sites and landfilling. This study enumerates the suitability of utilizing magnesite mine wastes in self-compacting concrete (SCC) as binder and aggregate replacements by considering the evaluation factors such as fresh, hardened properties, life cycle assessment (LCA) and eco-efficiency. The results from the experimental investigation revealed that aggregate blended SCC performed well in terms of both fresh and mechanical properties, while cement blended mixtures exhibited satisfactory results. Additionally, fly ash and magnesite mine waste substantially reduced CO2 emissions and costs with added strength benefits. Eco-efficiency evaluation of mine waste blended SCC reported up to 75% higher efficiency than conventional SCC.

Bioextraction of Magnesium as Plant Minerals from Magnesite Mine Wastes Collected from Salem District of Tamil Nadu, India

Magnesium (Mg) is an essential macronutrient that can be obtained through mineralization of mine spoils. The leftover mine spoils of magnesite mines still contain a reliable amount of Mg in it. The Mg present in raw magnesite spoils is in its carbonate form and hence it has to be mineralized to convert it into plant available soluble forms of Mg. The effect of B. cereus and B. stercoris in the mineralization of Mg has been studied in synthetic mineral salts medium (MSM). To obtain maximum mineralization results it is important to know the optimal conditions of the organisms under which they can grow and produce more Mg. The mineralizing capability of the individual organisms and their combined effect as a consortium under various concentrations of carbon source, pH, temperature and soil organic matter has been studied. It has been seen that the organisms grow and mineralize better when 1% of glucose has been supplemented as carbon source. The optimal pH and temperature were found to be pH 7 and 35°C, respectively. The addition of anthraquinone-2-sulphonic acid (ADQS) as soil organic matter enhances the mineralization Mg in synthetic medium. Rendering to SEM and EDX analysis, the mineralization of Mg in the synthetic medium was established.

Preparation of magnesium oxysulfate cement with semidry carbonation high calcium content light-burned magnesium (Ca-LBM)

With the large amount of high-quality magnesite mining, low-grade magnesite is discarded, which not only pollutes the environment but also wastes resources. Therefore, to utilize high-calcium magnesite tailings, carbonated light-burned magnesium with a high calcium content was used to prepare magnesium oxysulfate (MOS) cement. Characterization was performed by FT-IR, SEM, TEM, TG-DTG, TG-MS, MIP, XRD, and zeta potential measurements. The following conclusions are drawn: a porous shell layer was formed on the surface of the carbonated powder particles; thus, the hydration reactivity was reduced, but a better dispersibility was obtained. The setting time of the samples increased with increasing carbonation treatment time, and the early strength was lower than that of the control, but it increased significantly with the curing period. The 28 d compressive strength of the samples treated with carbonation for 2 min was 12.1 % higher than that of the control, and the volume density was 3.7 % lower than that of the control. In addition, a carbon-containing 517 phase (C- 517) structure was found. This C-517 phase exhibited better stability and resistance to sodium chloride erosion. After immersion in sodium chloride solution for 28 d, the softening coefficient was 0.84, which was 385 % of the control, so the carbonated samples had better durability than the ordinary MOS cement. The semidry method is used to carbonate light-burned magnesium with high calcium content, which avoids the negative effect of calcium oxide on the hydration process of MOS cement and provides a method to solve the discarding of high-calcium magnesite tailings.

Hibiscus rosa-sinensis as a potential hyperaccumulator in metal contaminated magnesite mine tailings

Mining is one of the major contributors for land degradation and severe heavy metals based soil pollution. In this study, the physicochemical properties of magnesite mine soil was investigated and assess the optimistic and eco-friendly remediation approach with Hibiscus rosa-sinensis with the effect of pre-isolated Acidithiobacillus thiooxidans. The physicochemical properties analysis results revealed that most the parameter were either too less or beyond the permissible limits. The pre-isolated A. thiooxidans showed remarkable multi-metal tolerance up to 800 μg mL−1 concentration of Cr, Cd, Pb, and Mn. Heavy metal content in polluted soil was reduced to avoid more metal toxicity by diluting with fertile control soil as 80:20 and 60:40. The standard greenhouse experiment was performed to evaluate the phytoextraction potential of H. rosa-sinensis under the influence of A. thiooxidans in various treatment groups (G-I to G-V). The outcome of this investigation was declared that the multi-metal tolerant A. thiooxidans from G-III and G-II showed remarkable effect on growth and phytoextraction ability of H. rosa-sinensis on metal polluted magnesite mine soil in 180 d greenhouse study. These results suggested that the combination of H. rosa-sinensis and A. thiooxidans could be used as an excellent hyper-accumulator to extract metal pollution from polluted soil.

Specific Solution of 3d Deformation Vector in Mine Subsidence: a Case Study of The Košice-Bankov Abandoned Magnesite Mine, Slovakia

Specific Solution of 3d Deformation Vector in Mine Subsidence: a Case Study of The Košice-Bankov Abandoned Magnesite Mine, Slovakia

Phytoremediation efficiency of Vigna mungo with the amalgamation of indigenous metal tolerant bacterial strain on metal polluted agriculture soil

This research was performed to evaluate physico-chemical properties of farmland soil nearby the magnesite mine site. Unexpectedly, few physico-chemical properties were crossing the acceptable limits. Particularly, the quantities of Cd (112.34 ± 3.25), Pb (386.42 ± 11.71), Zn (854.28 ± 3.53), and Mn (2538 ± 41.11) were crossing the permissible limits. Among 11 bacterial cultures isolated from the metal contaminated soil, 2 isolates names as SS1 and SS3 showed significant multi-metal tolerance up to the concentration of 750 mg L−1. Furthermore, these strains also showed considerable metal mobilization as well as absorption ability on metal contaminated soil under in-vitro conditions. In a short duration of treatment, these isolates effectively mobilize and absorb the metals from the polluted soil. The results obtained from the greenhouse investigation with Vigna mungo revealed that the among various treatment (T1 to T5) groups, the T3 (V. mungo + SS1+SS3) showed remarkable phytoremediation potential (Pb: 50.88, Mn: 152, Cd: 14.54, and Zn: 67.99 mg kg−1) on metal contaminated soil. Furthermore, these isolates influence the growth as well as biomass of V. mungo under greenhouse conditions on metal contaminated soil. These findings suggest that combining multi-metal tolerant bacterial isolates can improve the phytoextraction efficiency of V. mungo on metal-contaminated soil.

Chromite ore addition to serpentinized magnesite mining wastes for the production of refractory products following thermal treatment

Taking a circular approach to mining facilities requires the further exploitation of produced solid wastes, which are now considered as potential raw materials. This research aims to the re-utilization of specific mining wastes, containing mainly geologically degraded serpentinized minerals, produced during the minerals’ enrichment process of extractive magnesite industry, combined with the addition of chromite ore, aiming to the upgrading of refractory properties of the product, by applying the appropriate thermal treatment. A representative sample examined, corresponding to the proper blending of different mineral waste samples from several waste piles of mining area, combined with various chromite ore’s content, followed by the investigation of optimum thermal treatment, considering the applied temperature and time. The scope was to maximize the (desired) forsterite mineral phase in the product and, hence, to improve its refractory properties. The optimum results (e.g., considering the firing shrinkage level and the mechanical strength) achieved by the application of thermal treatment at 1300 °C and after heating time for 120–240 min. The refractory properties generally improved after mixing of examined mining wastes and chromite ore, due to the achievement of the best molar ratio of constituents [MgO]/[SiO2] = 2.2, regarding the additive, enhancing the formation of forsterite, whereas the application of heating temperatures over 1300 °C led to the melting of enstatite mineral phase, resulting to the degradation of product. The obtained results reveal that the produced sintered products can exhibit better refractory properties, and can be used as refractory raw materials for relevant applications up to 1300 °C.

Catalogue of South African mine tailings for geochemical carbon dioxide removal purposes

South Africa has the potential to be a global leader in implementing strategies targeting geochemical carbon dioxide removal (CDR) using mine tailings, utilising methods for alkalinity production and mineral carbonation. This is due to the hundreds of millions of tonnes of geochemically and mineralogically suitable tailings produced annually from diamond, PGM, chrome, nickel, phosphate, copper, talc and magnesite mines, exploiting mafic and ultramafic rocks. This approach may offer an additional route towards emissions offsets and reduction targets for South Africa.Here, a catalogue of tailings has been developed to highlight overall national CDR potential, drawing attention to site opportunities for pilot schemes. It has been calculated, using bulk geochemistry and shrinking core modelling, that South Africa has an average 1.1-1.7 MtCO2 removal capacity per year across all suitable sites, while an additional 11-17 MtCO2 could be removed through weathering historic tailings. The total CDR that could be achieved over the 2030-2100 period, considering all annually produced tailings available to weather, is 79-119 MtCO2. The capacity may be higher if mines of limited production information are considered, and pre-2017 tailings production amounts, abandoned stockpiles, and other industrial by-products are included. Diamond mines hold the highest geochemical CDR capacities, along with high tailings producers in Phalaborwa, Nkomati and Mogalakwena metal mines. There are incentives for academia, industry and policymakers to revise the geochemical CDR potential of mine sites in the years to come, and for other countries to catalogue their own suitable tailings and geochemical CDR potential capacities for future Mt-scale opportunities.

MagWasteVal Project—Towards Sustainability of Mining Waste

In the direction of sustainable mining solid waste management and eventually zero-waste production, the MagWasteVal research program aimed to achieve the proper handling of massive quantities of extractive mining waste originating from the magnesite mines after the enrichment process of useful ore. The main objectives of this project were both the investigation of geochemical variables affecting the serpentinization process (degradation) and the respected exploitation and further valorization of stocked-pilled solid (inert) wastes in the mining area. The study of thermal treatment (considering the heating duration and heating temperature) and the addition of various additives (alumina, chromite ore, run of mine, iron oxide, and magnesia) showed that the optimum upgrade for the mining waste samples occurs when a combination of magnesia (according to the optimum defined molar ratio: [MgO] + [FeO])/[SiO2] = 2) and iron oxide of approximately 2.5% is applied at both 1300 and 1600 °C for 120 min. The final products of the MagWasteVal project may have various potential applications, even on a large scale, for the production of alternative refractory materials/services, substituting other raw materials, and presenting both economic and environmental benefits.

Application of cement treated magnesite mine tailings as subgrade

Magnesite Mine Tailings (MMT) collected from Salem magnesite dump site are evaluated for their application as subgrade in road construction. Ordinary Portland Cement (OPC) was added to MMT by 2%, 4%, 6%, 8% and 10% of its dry weight and compaction characteristics, Unconfined Compressive Strength (UCS), Ultrasonic Pulse Velocity (UPV), California Bearing Ratio (CBR), durability characteristics and leaching characteristics were studied. In addition, X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Energy-Dispersive X-ray spectroscopy (EDX) analyses were carried out to explore the stabilisation mechanisms. The addition of OPC aided in producing a denser mix. The strength characteristics have revealed that the addition of OPC increases the strength of OPC-MMT mixes. The relationship between UPV and UCS is established to help in non-destructive evaluation. Nonetheless, higher cement content is mandatory to withstand the durability cycles. The stabilized mixes have fulfilled the environmental regulatory limits. The XRD, FESEM and EDX analyses have shown the products of hydration and alkali-magnesite reactions. This study finds that the cement treated MMT can be used as a subgrade in road construction which will not only reduce the negative environmental effects of open dumping of MMT but also replaces the natural soil in subgrade construction.

Effects of MgO and Fe2O3 Addition for Upgrading the Refractory Characteristics of Magnesite Ore Mining Waste/By-Products

In the context of a circular economy/zero-waste, the conversion of extractive wastes into new products is of particular importance. At the Grecian Magnesite SA mine (Chalkidiki, N. Greece), millions of tons of waste accumulate in the operation field. To achieve these goals, the effect of caustic calcined magnesia (MgO) at 10, 15, and 20 wt.% was investigated in combination with 0.5, 1, 2.5, and 5 wt.% Fe2O3 at 1300 °C and 1600 °C for 120 min. The main refractory properties were determined along with the mineralogical content. The morphological examination has been performed by SEM-EDS analysis. The addition of MgO increases the desired olivine and eliminates the unwanted pyroxenes, causing the formation of magnesium-ferrite and periclase. MgO wt.% addition resulted in the decrease of firing shrinkage at 1300 °C but increased with Fe2O3. At 1600 °C, firing shrinkage had a minimum value at the optimum MgO dose. Mechanical strength at 1600 °C achieved a maximum value at the optimum MgO dose plus 5 wt.% MgO and 2.5 wt.% Fe2O3 due to sintering process/magnesioferrite formation. These results indicate that MgO and Fe2O3 upgrade the refractoriness of magnesite mining wastes due to the diffusion of Fe2O3 in MgO excess.

Bioremediation competence of Aspergillus flavus DDN on pond water contaminated by mining activities.

This research was performed to evaluate the possibilities of reducing the physicochemical properties of polluted pond water situated around the magnesite mine tailing through indigenous metal tolerant fungi. The physicochemical analysis results revealed that most of the physicochemical properties of pond water sample were crossing the permissible limits. From the muddy pond soil sample, Aspergillus flavus DDN was identified (through molecular characterization) as predominant metal tolerant fungal strain and it showed resistance to Cr(VI), Pb(II), Zn(II), Cd(II), and Mg(IV) up to 1000μgmL-1 concentrations. This strain also effectively reduced (through biosorption) these metals in a short duration of the bioremediation process. In a lab-scale bioremediation study, the A. flavus DDN significantly reduced most of the physicochemical parameters crossing the permissible limit in polluted pond water in the presence of FM1 minimal media in 10 days of incubation. The dissolved oxygen level was significantly increased up to 74.91% from 5.86±0.39 to 10.25±0.95 in 10 days of treatment. The metal reduction and other physicochemical properties reduction were directly related to the biomass of A. flavus DDN. These findings suggest that A. flavus DDN can remove pollutants from magnesite mine tailing polluted pond water because elevated fungal biomass resulted in the highest percentage of pollutant reduction from the sample.

Exploitation of the fine rejected run of mine (ROM 0–4 mm) material to produce refractories in combination with the mining by-products of magnesite mine

Fine rejected fraction run of mine (ROM) material, which is rich in magnesite and cannot be further exploited, was mixed with mining wastes by-products of magnesite mine “Grecian Magnesites SA” (Gerakini, Chalkidiki, N. Greece), to produce refractories. The exploitation of the ROM in combination with mining wastes was investigated with the application of different thermal treatments, aiming to find the optimum thermal treatment process for upgrading the refractory properties of these samples. The examined firing process parameters, were the two final temperatures of 1300 °C and 1600 °C at different dwell times. Firing shrinkage, water absorption, apparent porosity, bulk density, and mechanical strength were determined, as the main parameters of importance. Furthermore, optical microscopy micrographs were appropriately received, while the mineralogical characterization was determined by X-Ray Diffraction (XRD) measurements. Concerning the optimum firing process regarding final temperature and dwell time for improving refractoriness of mining samples mixed with ROM, the results indicate that the best results were obtained firing at 1300 °C for 120 min. In that thermal treatment process, were observed the minimum values for firing shrinkage, water absorption, and apparent porosity and maximum values for bulk density and mechanical strength, which is the desired scope regarding these properties for improving refractoriness of the samples. The XRD patterns reveal that firing at 1300 °C with increasing dwell time olivine (forsterite) percentage increased, while pyroxenes (enstatite ferroan) decreased. Preheating of the samples at 850 °C did not significantly affect the physical properties of the samples, since firing shrinkage had a small decreasing trend, while bulk density and mechanical strength also decreased, degrading the properties of the samples. Thermal treatment at 1600 °C, showed a negative effect due to the significant reduction of mechanical strength combined with the major increase in firing shrinkage. Also, quantification of mineral phases at 1600 °C is rather misleading, due to the presence of high glassy/amorphous phases.