Rock Powder Research Articles

Accounting of weathering enhancement by mafic mineral spreading for CO 2 storage

The reduction of atmospheric CO 2 is an urgent global issue in the mitigation of global warming. Carbonate acts as a carbon sink in Earth's surface layer, and the weathering of terrestrial silicates and the deposition of oceanic calcium carbonate and organic matter mainly determine atmospheric and oceanic carbon dynamics on geological time scales. Various CO 2 reduction approaches have been evaluated, and the weathering acceleration method is expected to be a low-cost approach. This study attempts to estimate carbonate precipitation potential and dissolution rate from alkali leaching rates using weathering tests on mafic rocks. Based on Japan's annual average rainfall, the in situ carbonate precipitation potential obtained by spreading an olivine mineral or basalt rock powder at 40 ton-powder/ha was on the order of 10 -3 ton/year/ton-rock. This weathering rate could not be greatly accelerated under natural temperature conditions and fine granulation of the minerals.

Genesis of the Haopinggou breccia-hosted Au deposit, western Henan Province, China

Breccia-hosted Au deposits within the North China Craton (NCC) exhibit a complex genesis, with some breccias being genetically linked to Au mineralization and others unrelated. Understanding the origin of these breccias is crucial for elucidating the genesis of associated ore deposits and guiding exploration strategies. The Haopinggou deposit in the Xiong’ershan district, on the southern margin of the NCC, comprises quartz-carbonate vein-hosted Ag–Pb–Zn–Au deposits and related breccia pipe in metamorphic rocks of the late Archean to early Paleoproterozoic Taihua Group. The origin of the Haopinggou breccia is crucial to understand the Xiayu Ag-Pb-Zn-Au mineralization (5640 t Ag). In this study, we evaluate the genetic links between breccia and Ag-Pb-Zn-Au mineralization, with new insights obtained from the Haopinggou deposit characteristics, breccia characteristics, breccia-hosted Au mineralization, and isotopic data, which refine our understanding of Haopinggou Ag-Pb-Zn-Au hydrothermal systems and exploration models in discordant breccia pipes. Recent underground tunnel surveys and drill-core logging reveal a close spatial link between the breccia and hidden granite porphyry. Juvenile magmatic clasts (granite porphyry) and cement (K-feldspar and quartz crystallized from granite porphyry) are present in the breccia pipe above a granite porphyry apophysis, indicating that the breccia was formed by phreatomagmatic brecciation caused by emplacement of the granite porphyry. Fluidization at the cm- to 100-m-scale reveals that the movement direction of clasts inside the breccia pipe was from northwest to southeast after crypto-explosion, creating a northwest-trending breccia zone. Anhedral monazite (131.2 ± 7.6 Ma) encapsulated in pyrite from the breccia constrains the upper limit of brecciation. The δ34S values of pyrite in rock powder and hydrothermal cements range from 3.8 ‰ to 5.3 ‰ (mean: 4.8 ‰) and 2.7 ‰ to 7.5 ‰ (mean: 5.2 ‰), respectively, with δ34S-sphalerite in hydrothermal cement ranging from 5.7 ‰ to 6.1 ‰ (mean: 5.9 ‰) and δ34S-chalcopyrite ranging from − 0.9 ‰ to 5.6 ‰ (mean: 2.9 ‰). The S isotope characteristics of vein-hosted and breccia-hosted mineralization zones are consistent, with complete alignment of the sulfide assemblages and alteration features. These pieces of evidence collectively indicate that both vein- and breccia-hosted mineralization zones are products of magmatic activity. The metallogenic model for the Haopinggou breccia pipe underscores its unique formation mechanism, driven by pre-existing northwest-striking structural weaknesses and fluidization, indicative of a predominant northwest–southeast clast movement, and suggesting the potential for deep-seated porphyry-type Au mineralization.

Sewage sludge ash as filler in asphalt mastic: Low-temperature towards high-temperature performance

The sewage sludge ash (SSA) is characterized as a by-product used in the pavement industry to mitigate the environmental risks, enhance the landfill capacity and conserve the non-renewable resources. This research utilized SSA as a filler substitute in asphalt mastic, and its performance-based properties from low towards high temperatures were evaluated. For this goal, the physical and chemical properties of SSA and rock powder (used as base filler) were determined using BET surface area measurement, X-ray fluorescence, and scanning electron microscopy tests. The performance of base and SSA-modified asphalt mastics in four filler/bitumen weight ratios (0.6, 0.8, 1, and 1.2) was investigated using dynamic shear rheometer, multiple stress creep and recovery, linear amplitude sweep, and bending beam rheometer tests across a wide temperature range. The results indicate that SSA has a higher specific surface area, better bitumen absorption, and lower density compared to the base filler. Additionally, unlike the acidic nature of the base filler, SSA possesses strong basic properties, leading to a stronger chemical bond with bitumen and enhanced resistance to aging, particularly at high temperatures. Moreover, the lower density of SSA escalates the amount of filler per unit volume of the SSA-modified asphalt mastic, leading to the increased stiffness and elasticity. This trend improves resistance to permanent deformation and cracking at medium temperatures, although it has an adverse effect on performance of mastic at low temperatures. Moreover, due to the improved performance of SSA-modified asphalt mastic, this study can contribute to the sustainable development of the pavement industry.

Preliminary Study of Stone Sawing Sludges-based Alkali Activated Materials (AAMs) for the Conservation of Archaeological Ceramics

This paper presents research into the feasibility of using stone sawing sludge-based Alkali Activated Materials (AAMs) for conservation of Cultural Heritage. Sawing sludges are a stone processing waste product resulting from the mixing of rock powder with the water used to cool down the cutting blades. The chemical composition of the sawing sludges, when aluminosilicatic, is suitable for acting as a precursor to produce AAMs. AAMs are known for their low environmental impact and versatility since their existence is drawn from recycling waste materials. One of their possible applications is in the conservation of Cultural Heritage objects. This work presents a preliminary investigation into three sawing sludge-based AAMs with different mineralogical compositions and contributes to formulating guidelines for applying them as fillers on modern and archaeological ceramic pottery based on the evaluation of their workability, appearance and physical properties over time from the moment of application and up to 30 days. Dynamic Vapor Sorption and X-Ray Diffraction results provided an overview of the structural and mineralogical changes under high RH conditions, where the tested AAMs showed a type II isotherm curve, as expected for concrete-like materials, as well as disappearance of thermonatrite after one isothermal cycle. Ultrasonic Pulse Velocity test demonstrated the general homogeneity of the AAMs despite the lower velocity exhibited by one of the formulations, probably due to its internal pore distribution and possible presence of microstratification. The Oddy tests, application tests and colourimetric measurements evidenced the advantages and weaknesses of the AAMs, with overall encouraging results ensuing investment in further in-depth studies of these innovative conservation materials in view of their future use in the field of conservation of Cultural Heritage as a result of a circular economy model.

Let the dust settle: Impact of enhanced rock weathering on soil biological, physical, and geochemical fertility

Terrestrial enhanced rock weathering (ERW) is a promising carbon dioxide removal technology that consists in applying ground silicate rock such as basalt on agricultural soils. On top of carbon sequestration, ERW has the potential to raise the soil pH and release nutrients, thereby improving soil fertility. Despite these possible co-benefits, concerns such as heavy metal pollution or soil structure damage have also been raised. To our knowledge, these contrasted potential effects of ERW on soil fertility have not yet been simultaneously investigated. This field trial aimed at assessing the impact of ERW on biological, physical, and chemical soil properties in a temperate agricultural context. To do so, three vineyard fields in Switzerland were selected for their distinct geochemical properties and were amended with basaltic rock powder at a dose of 20 tons per hectare (2 kg.m−2). On each field, basaltic rock powder was either applied one year before the sampling campaign, one month before the sampling campaign, or not applied (control) for a total of 27 plots with 9 repetitions of each level. Overall, basaltic rock powder addition had a predominantly positive to neutral effect on soil fertility. Most soil properties showed no significant change either 1 month or 1 year post application. Nevertheless, our study highlighted a significant increase in earthworm abundance (+71 % on average), soil respiration (+50 %) and extractable sodium concentration (+23 %) as early as 1 month post application. The higher soil respiration raises the question of CO2 losses from organic matter mineralization that could limit ERW's efficiency. The increase in sodium raises concerns about a sodification risk potentially damaging soil fertility. These elements now require further investigation before enhanced rock weathering can be considered a viable and secure carbon dioxide removal technology.

Intrasample osmium isotope disequilibrium in young volcanic rocks: Insights from a new progressive digestion procedure

Some young volcanic rocks have been found to possess intrasample Os-isotope heterogeneity. This has important implications for source tracing and dating. Here, we use a new procedure through which it is possible to sequentially extract, from a single aliquot, the 187Os/188Os ratio of: i) the surface contaminant(s) (hydrobromic acid leachate); ii) the residual bulk rock powder (Step I) and iii) the Os-bearing phases entrapped within silicates (Step II). We applied this technique to two young basaltic reference materials (RMs), USGS BHVO-2 and EN026 10D-3. The former samples the 1919 lava from the Kīlauea summit crater (Hawaii) and the latter is a basalt sample dredged from Mohns Ridge (Greenland Sea). Both rock standards have previously been shown to display large intrasample Os isotope heterogeneity. In addition to analyzing these RMs, we also analyzed the RM USGS BHVO-1 for comparison, as well as another sample from the Kīlauea 1919 summit eruption (Kil 1919-6) along with a picritic tholeiite from the Kīlauea Iki 1959 eruption.Our leaching results show that BHVO-2 is contaminated with a highly radiogenic and labile contaminant with 187Os/188Os ratio of 0.525 ± 0.021. Without leaching, the Step I 187Os/188Os ratios varied from 0.1399 ± 0.0013 to 0.1568 ± 0.0014 while those for Step II were uniform (average = 0.1286 ± 0.0006, N = 5). A comparison of Re, Mo concentrations and 187Os/188Os ratio of the leachates of BHVO-2 and its predecessor (BHVO-1) indicates that BHVO-2 was contaminated during preparation. After leaching, the Step I and Step II 187Os/188Os ratios of BHVO-1 and another sample (Kīlauea 1919-6) from the same lava flow are identical within error to that of the Step II ratio of BHVO-2. A picrite from the 1959 Kīlauea Iki eruption also analyzed using the new technique gives homogenous results for both the steps with an average 187Os/188Os ratio of 0.1302 ± 0.0005. The 187Os/188Os ratio of recent Kīlauea lavas is identical within error to that of the primitive upper mantle (=0.1296). The Kīlauea Os-isotope composition could represent a “common component” that occurs globally in many plumes. The Step I 187Os/188Os ratio of EN026 10D-3 is 0.136 with Step II ratio being 0.131 (N = 2). The Step II 187Os/188Os ratios are more radiogenic than the nearby Jan Mayen lavas (187Os/188Os = 0.124–0.129) that have been argued to influence the chemistry of the Western section of the Mohns Ridge basalt but fall within the range of the Primitive Upper Mantle. We also discovered that BHVO-1, KIL 1919-6, 1959 Kīlauea Iki picrite, and EN026 10D-3 show Os-isotope disequilibrium between the leachate and Step I, suggesting wall rock assimilation during magma ascent. The data set presented here indicates a need for re-evaluating the extent to which mantle heterogeneities influence the Os isotope composition of ocean basalts.

The role of deformation on the early crystallization and rheology of basaltic liquids

This study highlights the rheological variation of magmatic systems during the early crystallization stage, which undergoes very different shear stress. Etna basaltic glass, made from natural rock powder, was used as a starting material. Nine shear rate-controlled experiments were conducted at 1150 °C (below liquidus temperature and undercooling degree ΔT ∼ 40 °C) with shear rates (γ˙) of 0.1, 1 and 10 s−1 using wide-gap concentric cylinder viscometry. Three additional experiments were conducted without spinning the melts (no shear, γ˙= 0 s−1). Run-products were collected after 3, 6 and 9 h. The experiment with the highest shear rate (γ˙=10s−1) showed a brittle failure when viscosity reached the value of 2.90 log (Pa·s) and after ca. 1150s. The measured viscosity matches the shear stress at 7244 Pa, corresponding to the brittle failure in our partly crystallised system at these conditions. After 9 h, the response of the partly crystallised Etna basalt to different deformation rates results in decreasing viscosity from 4.89 to 3.83 and 2.90 (log Pa s) as the γ˙ increases from 0.1 to 1 and 10 s−1, respectively. The main outcome of this study relates to the nucleation and growth of minerals with shear deformation. The deformation-free (γ˙ = 0 s−1) runs show the presence of only two phases: glass and Fe-oxides (Fe-ox) with only a few vol% (1–3) of oxides crystals after 3, 6 and 9 h. The deformation-bearing (γ˙ = 0.1, 1 and 10 s−1) runs show different scenarios: after 3 h, we observed only Fe-ox for a γ˙ of 0.1 s−1 (similar to deformation-free ones). As the shear rate increases to 1 s−1 and 10 s−1, solid phases after 3 h experiments are Fe-ox, plagioclase and clinopyroxene. Crystal growth rate depends on the applied shear rate: the highest rate is 1.1 × 10−6 cm/s and was measured for plagioclase after a 3 h experiment for γ˙ = 10 s−1. At γ˙ = 0.1 s−1, the plagioclase growth rate decreases to 2.70 and 1.35 × 10−6 cm/s as experimental time increases from 6 to 9 h, respectively. The vast range of shear stress and the systematic data obtained in this study are fundamental to deciphering crystallization dynamics suffered by magmas in volcanic reservoirs, dikes, conduits and lavas.

Comprehensive review of rock dust for soil remineralization in sustainable agriculture and preliminary assessment of nutrient values in micronized porous basalt rock from Nghe-An province, Vietnam

This review delves into the utilization of rock powder as a mineral-derived fertilizer to support soil remineralization in the context of sustainable agriculture. Soil remineralization has emerged as a key strategy for ensuring long-term soil fertility and reducing the dependency on synthetic fertilizers. This review critically assesses the methodological approaches applied in various studies, taking into account factors such as local rock mineralogy, soil conditions, crop types, and nutrient uptake by plants. The review covers a range of methods, including nutrient value analysis, assessment of nutrient release rates, crop cultivation experiments in both laboratory and field settings, and the resulting implications for soil remineralization. Additionally, we present findings from a preliminary study focusing on the nutrient content of basalt rock from Nghe-An Province, Vietnam. This experimental investigation is centered on the assessment of nutrient values in a specific porous basalt material, which has been processed into micro-nanometer particles using a high-energy ball mill, thereby enhancing nutrient release efficiency. The study employs a range of analytical techniques, including XRD, XRF, SEM/EDS, and ICP-MS, to quantify macro- and micro-nutrient compositions. While the basalt rock samples may exhibit limitations in providing macronutrients (such as K) compared to commercial azomite rock, they offer distinct advantages in furnishing secondary macronutrients (like Ca). This comprehensive analysis provides insights into the potential use of micronized basalt rock for soil remineralization.

Pyrolytic hydrocarbon generation characteristics of the Chang 7 shale based on different experimental methods: Implications for shale oil and gas in the Ordos Basin

Shale oil and gas resources are abundant in the Chang 7 shale of the Yanchang Formation in Ordos Basin. To determine the characteristics and influencing factors of hydrocarbon generation evolution of the Chang 7 shale, a series of thermal simulation experiments were conducted on low‐maturity shale and kerogen samples. The results indicate that the maximum yield of shale oil are 294.5 and 304.3 mg/g TOC for kerogen sample at heating rates of 20 and 2°C/h, and the corresponding experimental temperatures are 360.2°C and 408.0°C, respectively. The utilization of lower heating rates is favourable for shale oil generation and it is recommended to employ a lower heating rate during in situ heating processes to maximize the economic benefits. The formation of crude oil cracking gas begins when simulating temperature exceeds 528.0°C (Easy Ro 2.6%) at a heating rate of 20°C/h and 480.0°C (Easy Ro 2.5%) at a heating rate of 2°C/h, as indicated by the carbon isotopic composition of gaseous hydrocarbons. The maximum oil production rate of the rock powder sample is 159.8 mg/g TOC, which is lower than that of the kerogen sample. It suggests that certain minerals in the Chang 7 shale may impede hydrocarbon generation. After the addition of pyrite, the highest yield of shale oil is 213.96 mg/g TOC, 33.9% higher than the yield of the original rock powder sample, reflecting the positive catalytic effect of pyrite on hydrocarbon generation of Chang 7 shale. Under geologic conditions, pyrite catalytic hydrocarbon generation may act primarily on the migration of organic matter by macromolecules, which considerably increases the probability of direct contact between pyrite and organic matter. Therefore, the organic‐rich shale with high pyrite content in Chang 7 member is the preferred target for in situ conversion of shale oil and gas in the Ordos Basin.

A Study on Effect Analysis and Process Parameter Optimization of Viscous Acid Acidification in a Porous Heterogeneous Carbonate Reservoir

The homogeneous acid etching of conventional acid in porous heterogeneous carbonate reservoirs leads to a large amount of consumption in the near-wellbore area, which makes the acidification effect often not ideal. In order to improve the acidizing effect of porous heterogeneous carbonate reservoirs, viscous acid is used to increase the stimulation of the target block in this paper. Through systematic experiments, the adaptability of the viscous acid in the four layers of the M reservoir in the target block was evaluated, and the MD and ME layers suitable for acidizing stimulation were determined in combination with physical property analysis. Finally, based on the geological characteristics and experimental data of the preferred layers, a two-scale acid wormhole growth radial model was established, and the construction parameters of acidizing stimulation were optimized. The results show that (1) The preferred viscous acid system has a dissolution rate of more than 95% for the rock powder in the four layers. When the matrix permeability is high, the effect of the acid wormhole is obvious and the permeability increase is higher. (2) The steel sheet corrosion and residual acid damage experiments showed that the acid system was not corrosive to the wellbore, and the reservoir damage rate of the residual acid after the reaction was low. (3) Based on the relationship between reservoir porosity and permeability and the position of edge and bottom water, the MD and ME layers with more potential for acidizing stimulation are selected. (4) The results of the numerical simulation show that the optimal acid pump rate of the MD and ME layers is 1.4 bpm and 1.0 bpm, and the acidizing fluid volume is 255 bbl, which can form effective acid wormholes, and the range of reservoir permeability transformation is the largest. The field application results show that the optimization scheme effectively improves the production of oil wells, verifies the practicability of the scheme, and provides a reference for the process optimization of viscous acid in the same type of porous heterogeneous carbonate reservoir stimulation.

From waste to soil: Can we create functioning manufactured soils by recycling rock processing waste?

AbstractRock mining industries do not only exploit and transform extensive areas of land, but also produce vast amounts of rock waste material that lacks an adequate utilization. Some of these rock wastes have the potential to provide nutrients to plants and can therefore have positive impacts on soil properties. Consequently, we tested their potential for valorization as components of manufactured soils for use in urban areas. We conducted a 10‐week incubation experiment of soil mesocosms with sunflowers (Helianthus annuus L.) to evaluate the performance of manufactured soils with respect to plant growth and soil properties. We used three common rock materials (augite‐porphyry, greywacke‐hornfels, basalt), ground to powder and mixed into natural soils of either clayey or sandy texture. In order to test the performance under challenging environmental conditions, we applied a drought treatment in addition to a regular watering treatment. All manufactured soils were able to maintain plant growth, although the yield of aboveground biomass was significantly lower compared to the original soils. However, the effects of the water regime and the original soils on the overall plant growth were stronger than the effect of the rock powders, indicating that the manufactured soils were not hampering plant development more than challenging environmental conditions. The preparation of the manufactured soils altered the grain size distribution of the originally sandy and clayey soils. Since the rock powders contributed mainly to the silt‐sized particles, their addition to soils may improve the physical properties of the soil, especially the plant's available water content. We used wet‐sieving to isolate aggregate size fractions and thus analyse the formation of soil aggregates. The manufactured soils had a higher mass contribution of microaggregate‐sized particles, although this was mostly attributed to the presence of silt‐sized rock powder particles instead of aggregate formation. The total organic carbon (OC) content of the original soils was diluted in the manufactured soils, as the rock powders did not contain OC. However, the manufactured soils may have the potential for future OC storage due to the abundance of OC‐free mineral surfaces, which can retain organic matter as well as capture CO2 through enhanced weathering of primary minerals. Based on this work, the tested rock materials have the potential to be utilized as components in manufactured soils in the urban context that provide soil‐like functions, particularly in terms of sustaining plant growth. For improved results, additional measures to initiate a rapid development of soil structure are highly recommended, for example, by adding an easily decomposable source of organic matter.

Adsorption of Pb2+ ions of natural red lava rock powder in aqueous media

Red lava rock is available in nature and is formed from volcanic eruptions. Volcanic rocks are composed of oxides of diverse metals and have considerable porosity. In this study, lava rock powder was ground to a specific size and dried to test its ability to adsorb heavy metals in water. The morphology of the stone powder was observed to show crystals of 100–300 nm in size clumping into particles of a few μm. The phase structure is mainly in the form of Ca(Mg,Al)(Si,Al)2O6; in addition, the phases CaAl2Si4O12.2H2O, Ca2MgSi2O7, and Ca3MgSi2O8 also exist. The material's maximum Pb2+ ion adsorption capacity reaches 32.05 mg/g at endogenous pH. The isotherm of Pb2+ adsorption on the material follows the Langmuir model, and the adsorption kinetics are pseudo-first-order kinetics.

Recovery of Synthetic Diamonds from Fines of Natural Stones Processing

Objective: The objective of this study is to investigate the flotation process of the fines from the processing of natural stones - Fibro, and to propose a methodology to recovery synthetic diamonds present in it. For this, this research analyzes the influence of the amount of solid mass in the pulp and the amount of reagents used in the process. Theoretical Framework: The productive chain of natural stones generates millions of tons of Fibro annually, which can cause environmental damage if not disposed of or treated properly. Considering that the principles of circular economy are relevant in the pursuit of sustainable development of the sector, it is emphasized that Fibro contains several mineral resources that can be used in other productive chains. In addition to the rock powders resulting from processing, there are other particles of interest such as synthetic diamond. The synthetic diamonds present in Fibro come from the diamond tools used in rock sawing and polishing. These diamond particles have a high added value, and some recovery methods have been implemented to capture these grains for reuse. Among the methods used for this purpose, flotation has obtained the best results in previous studies. Method: The methodology adopted for this research begins with the collection and sampling of the Fibro in the natural stone production industries. Then, this material was classified granulometrically through sieving, and the samples were then subjected to the flotation process. In flotation, the percentage of solids in the pulp and the amounts of collector and frother used in the process were tested. All untested parameters were kept constant, and only the variables under investigation were modified at different levels. The methodology followed an experimental design and it was applied regression models and response surfaces for data modeling. Results and Discussion: The results show that the most efficient solid percentage was 35% in conditioning and 25% in flotation. Regarding the quantities of reagents tested, the model generated by the response surface indicates which levels obtained the best results in terms of concentrate recovery rate. It was also noted that the amount of collector had little influence on the process, which can be inferred by the natural hydrophobicity of the diamond. Implications of the Research: The implications of this research include economic benefits for the natural stones industry from the possibility of entering a new market in the sector. As well as advances in circular economy by reusing industrial waste and developing new technologies for the use of these materials. These results have the potential to impact industrial sustainability and can expand the mining and metallurgy sector. Originality/Value: This study contributes to the mining industry by proposing an innovative flotation methodology to recover synthetic diamonds from the fines of processing of natural stones. The relevance and value of this research are evidenced by its ability to provide a practical and efficient solution, with potential positive impact on circular economy and industrial sustainability.

Facile synthesis of a novel, efficient, reusable inorganic adsorbent from volcanic rock powder wastes and its application for the removal of dyes and metals from water

A new, efficient, and reusable inorganic adsorbent (NP.F) was easily synthesized using volcanic rock powder wastes (NP) as a precursor, with the synthesis of NP.F carried out at 550 ºC and with a ratio of NaOH (alkalinizing) and sample NP equal to 1. The samples were used in batch adsorption to uptake Ag+(aq.), Cu2+(aq.), acid green 16 (AG 16), and acid red 97 (AR 97) from aqueous solutions at pH 6.53, 5.98, and 2.3, respectively. NP and NP.F were characterized by different analytical techniques, such as XRD, FTIR, BET, TGA/DTG, etc. The adsorption kinetic carried out at 298 K for dye solutions with concentrations ranging from 50 to 200 mg L−1 and metals from 10 to 100 mg L−1 showed that data fit the pseudo-second-order mathematical model with rapid sorption and process equilibrium was reached after 30 min for dyes and 40 min for metal ions. The Sips model proved adequate to represent the adsorption isotherms of metallic ions and the dye AR 97, while the BET model represented the isotherms of the dye AG 16. The NP.F sample showed notable adsorption capacity for all the contaminants studied; for example, the adsorption capacity of the dye AR 97 was 295 mg g−1, while that of the Ag+ ion was 93 mg g−1. Besides, the adsorption of Cu2+(aq.) ion, dyes AG 16, and AR 97 were endothermic, while the adsorption of Ag+(aq.) was exothermic. Furthermore, even after numerous subsequent adsorption cycles, the NP.F sample maintained a high reusability, suggesting that the sample is qualified to be an adsorbent for removing contaminants from liquid effluents. In conclusion, NP.F could be easily converted into an efficient inorganic adsorbent for colorants and metals.

Study on explosion impact pressure and damage distribution law of rock powder segmented charge

The charge structure is the critical to determine the bench blasting effect of rock slope. Through theoretical calculation, model testing, and numerical simulation, a formula for calculating the stress attenuation of the axial hole wall of the segmented charging structure is proposed. Moreover, the influence mechanism of the explosive ratio and interval packing length on the internal damage distribution of the concrete of concrete specimens under a segmented charging structure of the cuttings is described. Finally, the research results are applied to the mining of a rock slope in southwest China. The research results reveal the following: 1) The pressure at the charge section is highest when the rock debris interval charge is used, and with the increase in the charge section distance, the pressure markedly decreases—sharply first before stabilizing. In the upper filling interval charge section, the minimum pressure corresponded to approximately the midway point of the filling section, and the stress distribution on the axial hole wall is concave: high at both ends and low in the middle. 2) The ratio of the upper and lower sections of the explosive column determines the form of blasting damage, and the range of blasting damage increases first and then decreases with the increase in the length of the rock debris in the interval section. 3) The field test shows that compared with the traditional blasting charge structure, the optimized segmented charge structure can reduce the blasting block rate by 13.1%. 4) Using the optimized charge structure, the explosive unit consumption can be decreased from 0.27 kg/m3 to 0.24 kg/m3, which improves the economic benefits of mining and construction of related mines.

Phonolite rock powder promotes adequate K and Na nutrition and cycling in eucalypt stands even during drought

Phonolite rock powder promotes adequate K and Na nutrition and cycling in eucalypt stands even during drought

Effect of Phosphate Rock Powder, Active Minerals, and Phosphorus Solubilizing Microorganisms on the Phosphorus Release Characteristics of Soils in Coal Mining Subsidence Areas

Effect of Phosphate Rock Powder, Active Minerals, and Phosphorus Solubilizing Microorganisms on the Phosphorus Release Characteristics of Soils in Coal Mining Subsidence Areas

SYNTHESIS AND CHARACTERIZATION OF NANOSILICA (SiO2) VOLCANIC ROCK OF MOUNT BATUR IN BALI

This research was conducted to synthesize and characterize silica minerals (SiO2) from volcanic rocks in the active volcano in Bali, namely Mount Batur. The synthesis carried out on five different color variants of this rock sample is by the coprecipitation method which begins with the process of taking rock samples on Mount Batur, crushing the rock until it becomes powder with a size of 100 mesh, washing with distilled water and drying, immersing the rock powder in the solution. 2 M HCl for 12 hours, then the results of the soaking were reacted again with 7 M NaOH solution as a hydrolysis process to obtain pure SiO2 in the sample. In the form of sodium silicate precursor (Na2SiO3), the sample was titrated with a 2 M HCl solution to obtain silica gel which was then washed and dried until amorphous silica powder was produced. The results of the XRF analysis showed that the SiO2 mineral content in the sample after going through the synthesis process was 94.9% and the Si element was 89.9%. The XRD characterization results show that the phase formed from the sample has a quartz structure with the highest peak at an angle of 2θ = 23.07o, then decreases and levels out at an angle of 2θ = 32.94o which is characteristic of an amorphous structure and with a silica grain size of 8.47 nm – 8.65 nm.

Performance of different fibre types in alkaline-activated concrete produced with industrial wastes: volcanic rock powder and blast furnace slag

The objective of the study is to determine the effects of different fibre types and ratios on the mechanical and physical properties of alkali-activated concrete (AAC) and to optimise important properties such as workability, unit weight, water absorption, compressive strength, modulus of elasticity and abrasion resistance of these concretes. Concrete samples were produced using steel and polyester fibres at ratios of 0.25%, 0.50%, 0.75% and 1%. The fibre ratios were varied, and various tests were conducted to determine the mechanical and physical properties of the concrete samples. The experiments clearly revealed the effects of fibre types and ratios on the performance of concrete. These results clearly demonstrate the effects of different fibre types and ratios on the mechanical and physical properties of AACs. Particularly noteworthy is the water-retaining property of polyester fibres, their effect on workability and their enhancing effect on abrasion resistance. The effects of steel fibres on compressive strength and modulus of elasticity are more pronounced, but they may present disadvantages in terms of workability and abrasion resistance. It is observed that mixed fibre usage provides a good balance in some properties. This study provides a roadmap for evaluating sustainable material options in the concrete industry and guiding future research.

Micro-sample Nd isotopic measurement on reference rock powders via the thermal ionization mass spectrometer Nd+ mode

The Sm–Nd isotopic system has been broadly utilized for dating and tracing in earth and planetary sciences. However, low Nd+ ionization efficiency permanently hinders precise and accurate measurements on small amounts of Nd samples. So far, isotopic measurement of micro-amount Nd sample via thermal ionization mass spectrometry (TIMS) Nd+ mode was mostly performed on Nd reference solutions, but less on natural rock or mineral samples. In the present study, analytical procedures to measure isotopic composition via the TIMS Nd+ mode were designed for natural rock powders by using 1–5 ng pure Nd. The analytical technique was refined through low-blank sample digestion, small-column chemistry for Nd extraction from matrix elements, loading Nd using purified H3PO4 solution, and careful heating of filaments before data acquisition. Measurements on small Nd amounts (1 ng–5 ng) of either the JNdi-1 reference solution or four reference rock powders yielded satisfactory results of 143Nd/144Nd value with respect to precision and accuracy. The analytical results agree well with the recommendation values of the reference materials within analytical errors and the internal precision is better than ±0.005 % (2RSE). When using 1 ng or 2 ng Nd amounts, 144Nd ion flow can remain stable in a signal intensity of >100 mV, and without the assistance of an additional ionization enhancer. Therefore, the analytical procedure, featured by low procedural blank (about 10–22 pg), high Nd+ ionization efficiency, and easy operation, has broad prospects for the application of Nd isotope in single-grain minerals or micro-samples.