Kaolin Residue Research Articles

29Si and 27Al NMR study of the structural transformation of calcined kaolin residue-based geopolymer using low alkali activator content for sustainable construction materials

Geopolymer commercialization efforts in parallel with unconventional research are the only pathway to achieve the large-scale deployment of geopolymer technology. Geopolymers with a low quantity of alkali activator produced by the compression process are one way to bring this technology to industry because of the higher strength and lower efflorescence of the product. In this work, calcined kaolin residue-based geopolymers with a low alkali activator content were synthesized by various Si/Al mole ratios with soluble silicate from Na2SiO3 to adjust the Si ratio. The effects of Si/Al mole ratios on the structural transformation, microstructure, and compressive strength of geopolymers containing low alkali activator content were studied. The structural transformation and microstructure of geopolymers were characterized by NMR, SEM, and BET, and the compressive strength was assessed using a mechanical testing machine. The results present that geopolymer synthesized with various Si/Al mole ratios of precursor materials impacted the change in polymerization degree of silicate species (Qn(mAl)) and aluminate species. The Q4(4Al) and Q4(3Al) structures were transformed into the Q4(2Al) structure, and the content of the AlIV structure decreased when the Si/Al mole ratio of geopolymer was increased to 1.58. However, the contents of Q4(4Al) and AlIV structures increased again when the geopolymer had a Si/Al mole ratio of 1.62. SEM/EDX and BET results of geopolymers presented denser matrices, more amorphous aluminosilicate gels, and higher Si/Al ratios in aluminosilicate gels, while the pore size and pore volume were quite small when the Si/Al mole ratio of precursor materials was increased. In contrast, the highest Si/Al mole ratio of 1.62 showed different properties. The compressive strength of geopolymer was maximized at a Si/Al mole ratio of 1.58, and the decline in compressive strength of geopolymer with higher Si/Al mole ratio was related to the contents of Si–O–Si, Si–O–Al, and Al–O–Al bonds, content of aluminosilicate gels, and properties of the microstructure. The geopolymer synthesis using calcined kaolin residue and low alkali activator content is considered an eco–friendly process, which uses waste materials and less chemicals, and obtains high-strength products.

Study of rheological properties of lime–metakaolin slurries

Lime–kaolin residue (metakaolin) slurries were rheologically characterized by high stress flow, low strain oscillatory, and creep and relaxation tests. All lime and lime–metakaolin slurries presented flow curves with rheological behavior, which is well fitted by the Herschel–Bulckley model. In addition, they exhibited a predominantly elastic behavior, acting as a viscoelastic liquid. The presence of metakaolin resulted in less rigid and more elastic slurries, reducing the initial yield stress and viscosity of the lime-based slurries, regardless of the metakaolin content.

Development of Eco-Friendly Mortars Produced with Kaolin Processing Waste: Durability Behavior Viewpoint

This study presents the development of new eco-friendly mortar compositions containing kaolin residues (KR) and assesses their durability behavior. Firstly, the natural and calcinated kaolin residues (600 °C, 650 °C, 700 °C, 750 °C, and 800 °C) were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), granulometric analysis, and surface area. The kaolin residue calcinated at 800 °C was chosen to be added to new compositions of mortar because it presented the best pozzolanic performance. The aging tests accomplished in internal (Ei) and external (Ee) environments were applied in mortars with a mass proportion of 1:2:6 (cement + KR: lime: sand), in which the KR, calcinated at 800 °C, replaced the cement in the mass fraction of 0%, 5%, 10%, 15%, 20%, and 30%. The Ei was performed for 30, 60, 90, 180, and 360 days, and the Ee for 90; 210; 360; and 512 days. After the aging tests were completed, the mortar compositions containing KR were evaluated to determine their mineralogical phases (XRD), compressive strength (CS), and thermal behavior (DTA and thermogravimetry). In summary, the KR addition to the mortar compositions decreases the mechanical resistance to compression; however, mortars with a substitution of 10% and 20% presented resistance values within the minimum limit of 2.4 MPa established by ASTM C 270.

A new eco-friendly mass formulation based on industrial mining residues for the manufacture of ceramic tiles

New eco-friendly mass formulations based on the scheelite and kaolin residues were developed to manufacture ceramic tiles. The start raw materials (scheelite residue, kaolin residue, feldspar and plastic clay) were characterized as to their chemical composition, main mineralogical phases, and particle size distribution. Three ceramic masses with 37 wt% of kaolin residues and different contents of the scheelite residues (2 wt%, 5 wt%, and 10 wt%) were formulated. The mass formulations were uniaxially pressed (19.6 MPa) to obtain samples with dimensions of 60 mm × 40 mm x 7 mm, which were dried at 110 °C/24 h, and sintered at different temperatures (1150 °C, 1200 °C, and 1250 °C). Dilatometric experiments measured thermal expansion coefficients. The results are in agreement with the literature, i.e., 6.0 μm/m°C−1, 6.1 μm/m°C−1 and 6.4 μm/m°C−1 to samples with 2 wt%, 5 wt%, and 10 wt% of scheelite residues, respectively. The potential of the mass formulations studied was evaluated by linear shrinkage, water absorption, apparent density, apparent porosity, flexural strength, and mineralogical phase identification. The results were compared with the literature experimental data and International Technical Standards. It was concluded that the samples investigated have suitable properties for use as ceramic and porcelain tiles. Also, the pseudowollastonite and mullite phases were identified in the sample with the lowest concentration of scheelite residue. These phases are responsible for increasing flexural strength.

Effect of Kaolin Addition into Metakaolin Geopolymer Composite

AbstractIndustrially produced metakaolin may contain raw kaolin residues. Therefore, the aim of this work was to determine the influence of kaolin remains in the metakaolin on the final geopolymer ...

Synthesis of CaO-SiO2 catalyst from lime mud and kaolin residue for biodiesel production

In the present work, synthesis of CaO-SiO2 catalysts using industrial wastes including lime mud and kaolin residue was proposed. The CaO-SiO2 catalysts were synthesized through a simple precipitation followed by calcination at 950 °C. The synthesized catalysts consisted of quartz, CaO and Ca(OH)2 proportion of which depended on CaO:SiO2 ratio. The catalytic activity was also investigated. The FAME yield reached up to 93% when the catalyst with CaO:SiO2 = 2 was used. However, it was found to decrease with numbers of reuse.

EFFECT OF KAOLIN ADDITION INTO METAKAOLIN GEOPOLYMER COMPOSITE

Industrially produced metakaolin may contain raw kaolin residues. Therefore, the aim of this work was to determine the impact of kaolin remains on the metakaolin and the final geopolymer quality. A series of mixtures based on metakaolin (Mefisto L05 by CLUZ Nove Straseci, Czech Republic) was prepared with the 0-60 wt% gradual addition of raw kaolin, and the mechanical strength of the final geopolymer products was tested. It was found that up to a 20 wt. % amount of kaolin in metakaolin does not weaken the geopolymer’s performance. Moreover, a geopolymer made of metakaolin with 2-4 wt% of kaolin showed slightly better mechanical properties than the geopolymers made from metakaolin itself.

Valorization of Mining Waste in the Synthesis of Organofunctionalized Aluminosilicates for the Esterification of Waste from Palm Oil Deodorization

The synthesis of aluminosilicate Al-MCM-41 was performed using mining kaolin waste as an alternative source of silicon and aluminum to add value to this waste. In a preliminary stage, acid leaching was carried out with the kaolin residue with three different durations (1, 1.5 and 2 h) to evaluate the leaching time that provided the highest amounts of silicon and aluminum in the tailings. Molecular sieves were synthesized by the hydrothermal method and calcined at 550 °C to eliminate the surfactant. X-ray diffractograms of the synthesized samples revealed that the sample AM41-2H, obtained from kaolin leached for 2 h (MC7-2H), presented the best structural arrangement due to the presence of 2θ angles close to 2.32°, a specific surface area of 1016 m2·g–1, a pore volume of 0.80 cm3·g–1, and a pore diameter of 3.14 nm, which are characteristic of Al-MCM-41. A sample of AM41-2H was functionalized with 3-mercaptopropyltrimethoxysilane (MTPS) (5 mmol MTPS/g AM41-2H). To eliminate excess unaltered MTPS on the sur...

Experimental investigation into the kinetics of Falcon UF concentration: Implications for fluid dynamic-based modelling

Centrifugal gravity separators, such as the Falcon UltraFine (UF) concentrator, are the most common gravity concentration techniques used for fine particles processing. Hence, understanding the kinetics and separation mechanisms at play within these separators is of paramount interest. Recent research yielded a predictive physical model for the Falcon UF which however does not explain some results obtained with industrial ores. The Falcon UF kinetics have been investigated through the processing of fine-grained ores from the Altenberg tin deposit (Germany), the Tabuaço tungsten deposit (Portugal), a synthetic iron ore as well as results from previous studies on kaolin residues. Results have shown an evolution of Falcon UF performance with time/feed mass in contradiction with the stationary separation hypothesis on which the physical model was based. In terms of Falcon UF separation timing, four phases can be distinguished. First, upon initial feeding of the bowl, particles are trapped or rejected depending on their settling velocity. It yields a relatively ineffective selection according to density so that only ultrafine particles are ejected from the bowl, resulting in the quick growth of the concentrate bed. When the bed reaches a critical size, recovery and enrichment continue to increase through selective resuspension phenomenon that favours the concentration of dense particles and the ejection of larger particles. This way, the bed builds up while the content of concentrate bed surface evolves until resuspension balances the stream of dense material reaching the bed and recovery drops. The evolution of partition curves over time confirmed the low recovery of ultrafine particles during the whole operation but also showed a decrease of coarse particles recovery with time. It suggests that the second separation mechanism is less sensible to particle size compared to the first one and that size even has a negative impact on recovery. Furthermore, erosion figures in furrows are observed in the concentrate bed which may play locally an active role in the separation. These observations suggest that two separation mechanisms are at play. Firstly, differential particles settling within the flowing film which is already accounted for in the existing physical model. Secondly, resuspension of particles from the concentrate bed by the action of a lift force acting preferentially on coarse particles deposited at the surface of the bed and resulting in the rejection of coarser and lower-density particles. The addition of a lift force component to the existing model is discussed and a resuspension criterion is proposed as a guidance of the physics involved in this second separation mechanism. Future developments will require a dynamic model which would need to integrate the evolution of the concentrate bed content over time.

Characterization of Kaolin Residues from the Jarí Valley Reservations Provided by Cadam S/A Company

The ceramic industry is one of the most important productive chains of the State of Pará, generating both money and employment. Kaolin has many industrial applications and new uses are constantly surveyed. Although the extraction and processing of kaolin contribute to the economy growth, the activity also provokes serious environmental issues. Being aware of the environmental problem caused by the inadequate decomposition of kaolin residues from the beneficiation process of these minerals, which pollute and attack the environment, this paper aims the chemical, physical and mineralogical characterization of the kaolin residue from the post-treatment disposal provided by CADAM S/A company. The main oxides in the residues were SiO2and Al2O3. In the X-ray diffraction analysis it was verified that the kaolin residue is basically formed by kaolinite and quartz, in the particle size analysis it was observed that the medium size of the particle was of 1,77 μm.

Ceramic Membrane Made with Inorganic Residue

Industrial wastes reuse becomes attractive to raw materials economy and to avoid environmental problems. The aim of this study is to develop and characterize tubular ceramic membranes using in their composition inorganic residues generated in the industries, such as, granite, alumina residue from calcination process and kaolin. Initially, it was performed the physical chemical and mineralogical characterization of the residues. Different formulations of ceramic masses have been studied with incorporation of residue, clay and additives for producing tubular membranes through the extrusion process. The membranes were characterized by SEM and flow measurements with distilled water. The membranes were applied to effluent treatment from textile and oil industry. The granite residue showed a high content of SiO2and Al2O3in its chemical composition and significant amount of iron and calcium oxides resulting from the granite processing. The granite residue presented average particle size of 13.98 µm. The residue from alumina process contain gibbsite and α-alumina, and average particles size of 15.68 µm. The residue from kaolin processing presented high content of quartz and alumina and average particles size of 29.0 µm. The tubular membrane produced with granite residue presented porosity from 17 to 30%, pores size in the range of 0.06 to 0.14µm and water flow from 10 (at 2 Bar) to 24 L/h.m2(at 4 Bar). These membranes retained 100% of indigo particles and was effective in the separation of indigo. The membrane prepared with alumina residue presented porosity close to 58% , pore size of 0.96 µm and water flow from 68 to 80 L/h.m2(at 2 Bar). These membranes were applied with successes in the separation of water from emulsion (100 ppm oil/water) with rejection above 96%. The membrane prepared with kaolin residue presented pore size from 0.16 to 0.22 µm, porosity from 41 to 44% and water flow from 53 to 70 L/h.m2. The ceramic membranes with industrial residues were successfully produced and applied in the treatment of industrial effluents.

Effect of highly processed calcined kaolin residues on apple water use efficiency

Processed calcined kaolin particle films (PKPF) have been shown to repel some insects and reduce various environmental stresses often resulting in improved yield and quality of horticultural crops. PKPF studies in the literature have various water use efficiency (WUE) responses. The purpose of this study was to evaluate 2 application rates of PKPF (3% and 12%) on the whole tree water use efficiency and compare gas exchange values with carbon isotopic discrimination and seasonal water use efficiency in order to determine if there are consistent effects on WUE in apple and infer the mechanisms of action. Fruit yield and total biomass influence WUE whether WUE is measured directly in whole plant chambers, estimated by biomass/unit evapotranspiration, or Δ13C. Δ13C analysis of WUE generally found that the untreated control had lower values and therefore higher WUE than PKPF treatments. Whole plant gas exchange analysis of WUE generally lacked the sensitivity to identify the treatment differences observed using Δ13C analysis and those treatment differences identified were contrary to Δ13C analysis. A lysimeter study supported the reduced WUE of PKPF treated plants by demonstrating increased E with a range of PKPF residue amounts. The lysimeter results suggest that for well-watered and presumably non-stressed conditions, gas exchange is limited by leaf temperature and the concomitant leaf-air vapor pressure deficit that influence stomatal conductance. When leaf temperature is reduced by PKPF, the response results in increased stomatal conductance and gas exchange, as measured by increased E. The reduction in WUE by PKPF treatment is balanced by an increase in overall gas exchange and increased yield and quality.

Modelling heavy and gangue mineral size recovery curves using the spiral concentration of heavy minerals from kaolin residues

Spiral concentrators are one of the most common gravity processing methods extensively used for the concentration of mineral based on their density, particle size and shape. As for every gravity concentration technique, particle size plays a major role in the separation mechanisms within the spiral. Thus, in addition to classical performance indices, such as grade or recovery, partition curves are also a valuable criterion for quantifying the separation efficiency. In this paper, we study and model the influence of wash water additions and pulp density on heavy and gangue mineral partition curves using kaolin residue enriched in heavy minerals and via a design of experiment (DOE). The results show that coarse particle size recovery curves are affected by a systematic decrease, which is mainly impacted by wash water additions. Partition curve modelling through particle size distribution and DOE regression model fitting allow a better understanding of the effect of wash water on the aforementioned phenomenon for each mineral fraction. Gangue minerals are more affected by this phenomenon, which has been interpreted as a result of the Bagnold effect and secondary flows within the spiral. A decrease in the coarse particle recovery represents a significant source of losses, and a better understanding of this phenomenon is necessary to avoid these losses.

Effect of highly processed calcined kaolin residues on apple productivity and quality

Calcined kaolin-based particle films (PKPF) are effective in reducing insect, heat, photosynthetically active radiation (PAR) and ultraviolet radiation (UV) stress in plants due to the reflective nature of the heat-treated particles. The purpose of this study was to determine the effects of PKFP treatments applied at moderate (3%) and high rates (12% w/v) on apple physiology, yield and quality and the interaction with ambient ozone levels for a 6 year period. Fruit mass was increased by applications of PKPF at 3% and 12% in 4 of 6 years in non-irrigated treatments and in 2 of 6 years in irrigated treatments. Red fruit color was increased (lower hue angle) over the control in 5 of 6 years and in 2 of 5 years the 12% PKPF had improved red color over both the 0% and 3% PKPF non-irrigated treatments. PAR interception over 6 years, adjusted for LAI, was greatest for the control, least for the 12% PKPF, and 3% PKPF was intermediate. Reduced PAR interception below the canopy was likely due to greater PAR reflection within the canopy. Whole canopy temperature was significantly higher for the control (26°C) and lower for the 3% and 12% PKPF treatments (24°C). Fruit mass increased in the PKPF treatments, relative to the irrigated control treatment (%), with increasing maximum ozone levels during May. In laboratory studies, ozone degradation was greatest for alfalfa, least for calcined kaolin and the addition of alfalfa to calcined kaolin increased degradation proportionately. The present study confirms that calcined kaolin is an effective catalyst for ozone degradation and organic materials, such as alfalfa, are even more effective, due to the direct reaction with carbon molecules. Whole canopy gas exchange measurements (1000–1600HR) over a 10 day period in 2011 indicated that the 2.7% PKPF+0.3% alfalfa dust consistently had higher photosynthesis, 0.3% alfalfa was intermediate, while the control and 3% PKPF had the lowest photosynthesis rate. Whole canopy ozone degradation indicated that the 2.7% PKPF+0.3% alfalfa dust consistently had the greatest ozone degradation, 3% PKPF and 0.3% alfalfa were intermediate and the untreated control had the least ozone degradation. There is evidence that the 0.3% alfalfa stimulated a small amount of microbial growth on the leaf surface while the 2.7% PKPF+0.3% alfalfa stimulated a much greater amount of microbial growth. This synergistic effect may be due to the increased surface area in the particle film providing habitat for microbial populations and the reflection of UV by the particles that can be deleterious to microbial growth within that habitat. Data support the concept that chronic ozone damage is moderated to a significant degree by the use of surface treatments that catalyze ozone degradation in a particle film. The use of PKPF may be one tool to mitigate not only increased ozone stress but also heat stress from increased growing season temperatures in the future.

Comparing univariate and multivariate approaches for process variograms: A case study

The classical application of theory of sampling (TOS) is univariate. However, most practical situations address multi-analyte issues, in which the common belief is that one should focus a variographic study on the analyte with the most heterogeneous distribution. This paper introduces a multivariogram approach to process sampling and compares it with the classical univariate and multivariate approaches of variograms as applied to principal component analysis (PCA) scores. A case study of low-grade kaolin residue sampling for metallurgical testing is used to illustrate this methodology. A total of eight important properties are analysed, including chemical analytes, size distribution properties and pulp density. The results show that the classical univariate approach can underestimate the global sampling error if the sampling protocol is designed by using only the highest variance property. Variograms that are calculated from PCA scores highlight distinct spatial patterns through variable grouping in a reduced number of variograms. Multivariograms can be used to summarise time variations in multiple analytes and highlight the multivariate time autocorrelation aspects of these analytes. However, the resulting sampling variance is very high, and an alternative approach that applies multivariograms to PCA scores, filters noise from the data, and only keeps relevant data information, which reduces the global sampling variance, is proposed. This case study illustrates the usefulness of multivariate approaches to help multivariate variographic modelling in mineral processing and in many other fields within science and industry that deal with multi-analyte sampling issues.

Concentração eficiente e econômica de caulim para a proteção de algodoeiro contra o bicudo

Resumo:O objetivo deste trabalho foi determinar a concentração de caulim mais eficiente e econômica para a proteção de algodoeiro contra os danos causados pelo bicudo-do-algodoeiro (Anthonomus grandis). Utilizou-se o delineamento experimental de blocos ao acaso, com cinco tratamentos de pulverizações com caulim nas concentrações: 20, 40, 60, 80 e 100 g L-1. Determinaram-se os seguintes parâmetros: percentagem de botões florais com orifícios de oviposição por fêmeas do bicudo; resíduos de caulim depositados sobre as folhas e as brácteas do algodoeiro; média da produção; e receita líquida do algodão, por hectare, a partir da pesagem da pluma de algodão com caroço. As percentagens de botões florais com orifício de oviposição variaram de 13,6 a 30,8%; o resíduo médio de caulim depositado nas folhas, de 0,0010 a 0,0034 mg mm-2, e nas brácteas, de 0,0010 a 0,0034 mg mm-2; a produção variou de 348,1 a 717,8 kg ha-1; e a receita líquida de algodão de R$ 1.033,88 a R$ 2.098,86 por hectare. As concentrações de caulim mais eficientes para a proteção de algodoeiro contra o bicudo são as de 60, 80 e 100 g L-1; no entanto, a de 60 g L-1foi a mais econômica.

A multivariate approach for process variograms

In the theory of sampling, variograms have proven to be a powerful tool to characterise the heterogeneity of 1-dimensional lots. Yet its definition and application in sampling for mineral processing have always been limited to one variable, typically ore grade. However this definition is not adapted to sampling for mineral processing where samples contain multiple properties of interest, i.e. variables, such as multiple element grades, grain size, etc. For such cases, the multivariable variogram, originally developed for spatial data analysis, can be used to summarise time variation of multiple variables (e.g. ore characteristics which are important for the process) and highlights the multivariate time auto-correlation of these variables. A case study of low-grade kaolin residue sampling for gravity processing shows that the multivariogram summarises the overall variability and highlights a periodic phenomenon when all variables are taken into account. This example illustrates the potential of the multivariable variogram compared to the classical approach.

Sinthesys of Mullite Using Microwave Furnace from Kaolin and Alumina Residue

Heating with microwave power is a process in which the materials take up electromagnetic energy volumetrically and turn it into heat inside a piece. This is the great difference from the conventional method, where the heat flows between objects by means of conduction, radiation and convection, in which the surface of the materials is heated first, and then the heat is transferred to the interior of the piece, thus forming a temperature gradient. On the other hand, microwave heating generates heat first inside the piece, heating the whole volume later. [1]

Kaolin Residue as an Alternative Binder for Grout Seat and Revetment

The kaolin residue presents in its composition significant levels of sílica and alumina, making it a material with chemical and physical properties appropriate to use as an alternative material with pozzolanic characteristics in substitution to the cement for grout utilization. Thus, this work aimed evaluate the influence from the addition of different amounts of kaolin residual calcined in partial substitution of Portland cement on grout in dash 1:2:6 (cement+%residue:lime:sand). It was evaluated grouts with and without residue substitution in the strengths of 0%, 5% and 30%, through resistor the simple compression at 30, 60 and 90 healing days. The results of resistor from the grouts were over the one required by NBR 13281 [, classifying them as type I e II.

Algal Community Composition from Kaolin Recovery Ponds Located in Middle Georgia

This is the first floristic and ecological evaluation of small pond systems developed over different periods of time after seized kaolin mining operations. Assessment of the total algal assemblage was used to infer environmental conditions of the aquatic habitats and also provided information about the ecological health and integrity of the aquatic ecosystems. The main objectives of this study were to document algal community composition and discern the amount of time it takes for a mined pond to reach its high biodiversity of primary producers. Winter and summer samples were taken from a pond developing for two years after removal of kaolin and from a pond that was thirty years old. Both pond systems contained rich algal communities predominantly from Cyanobacteria, Bacillariophyta, and Chlorophyta; however, the 30-year pond had higher Shannon-Wiener diversity, richness, and evenness values in both sampling seasons. In winter, filamentous Zygnematales dominated algal communities in the 2-year pond, while the 30-year pond community was dominated by diatoms. In both sites, the most taxon- rich group was green algal representatives of Desmidiaceae. In summer, potentially toxin- producing filamentous Cyanobacteria of the Nostocales were recorded in the 2-year pond, while the 30-year pond had higher average algal cell evenness and few toxic Nostocales. The average abundance of 11 diatom species, seven green algae, and one representative each of Euglenophyta, Cyanobacteria, and Cryptophyta resulted in less than 20 percent overall similarity between the two ponds. Our findings suggest that after two years of development potentially harmful kaolin residues are removed by natural sorption processes and do not negatively influence primary producers. However, stabilization processes in those manmade ecosystems may potentially take more than two years to produce high species richness and prevent toxic algal blooms.