Use of granite sawing wastes in the production of ceramic bricks and tiles

Granite process industry generates a large amount of wastes, which pollute and damage the environment. This work aims to characterize and evaluate the possibilities of using the granite sawing wastes, generated by the process industries from Paraı́ba State, Brazil, as alternative ceramic raw materials in the production of ceramic bricks and tiles. Samples of granite sawing wastes were collected from companies located in Paraı́ba State. Their characterization were carried out with the determination of density, particle size distribution, surface area (BET), chemical composition, and by DTA, TGA, XRD, and SEM. In a second part of the work, tests in ceramic compositions were conducted in order to evaluate the suitability of addition of wastes in ceramic compositions used in the production of ceramic bricks and tiles. The results showed that the granite wastes have physical and mineralogical characteristics that were similar to those of conventional ceramic raw materials. The ceramic bodies produced from reformulated ceramic compositions had technological characteristics in agreement with the Brazilian standardizations for ceramic bricks and tiles.     

利用废物生产水泥的实施方案

阐述了宁夏英力特化工股份有限公司采用先进的生产技术和设备,充分利用聚氯乙烯树脂生产过程中产生的固体废物,生产水泥的实施方案。     

Use of glass polishing waste in the development of ecological ceramic roof tiles by the geopolymerization process

The production process of ceramic roof tiles requires a large consumption of natural raw material, such as clay, and energy consumption in the sintering process. Thus, the objective of this research was the development of more ecological tile for civil construction, adopting the process of geopolymerization, which does not require burning, and the use of glass polishing waste, in partial replacement of natural raw material. Prismatic specimens were made with a ratio of alkaline solution/ (metakaolin + waste) = 0.26 and variation of the curing time in 7, 28, and 60 days, and a ratio of precursors with SiO₂/Al₂O₃ varying in 2.5, 3.0, 3.5, and 4.0 for the evaluation of technological properties such as apparent specific mass, linear shrinkage, water absorption, and mechanical resistance to flexion, in addition to microstructural evaluations and the physical, chemical, and mineralogical characterization of the waste. The results showed that the glass waste had potential for use as a precursor in the geopolymerization process, and that the specimens with a 7 days cure and a SiO₂/Al₂O₃ = 4 ratio are the most recommended for the production of roof tiles for civil construction.     

Incorporation of the ash from cellulignin into vitrified ceramic tiles

The incorporation of the ash from cellulignin, a catalytic biofuel, into a clay/feldspar body was investigated. The cellulignin was obtained by acidic prehydrolysis and was then burnt in boilers leaving behind the ash as a solid residue. Characterization tests of the ash employed X-ray diffraction, particle size distribution, mercury porosimetry, chemical analysis, thermal analysis and high-resolution scanning electron microscopy. The ash/clay/feldspar compositions were fired at 1200 °C and the linear shrinkage, water absorption and flexural strength were determined. Solution and leaching tests were conducted to evaluate the environmental safety of the final ceramics. The results showed that the ash is mainly composed of quartz with partially nanometric particle size, high surface area and high content of alkaline and alkaline earth oxides. These are advantages for a potential use of this ash as a flux. The partial replacement of feldspar by ash promoted a better vitrification decreasing the open porosity and increasing the mechanical strength. Heavy metals present in the ash became inert after the firing stage.     

Reformulation of roofing tiles body with addition of granite waste from sawing operations

A ceramic body traditionally used to produce roofing tiles was reformulated by the addition of granite waste from sawing operations. The objective was to obtain a ceramic product with better technological properties. The main tool for the reformulation was the definition of the appropriate particle size of the raw materials as given by the Winkler diagram. The raw materials were characterized with respect to their mineralogical composition by X-ray diffraction, particle size distribution as well as chemical composition and plasticity. Specimens were made by extrusion and fired at temperatures from 850 to 1100 °C. The technological properties determined were: dry bulk density, linear shrinkage, water absorption and mechanical strength. Microstructural analysis of the fired samples was carried out by X-ray diffraction. The results showed that the granite waste contributes to reduce the plasticity and the linear shrinkage of the ceramic bodies. One reformulated ceramic body exhibited better values of water absorption and mechanical strength than the industrially used.     

Crystallization behavior and mechanical properties of high strength mica-containing glass-ceramics from granite wastes

The high-strength mica-containing glass-ceramics were prepared from granite wastes by bulk crystallization. The influences of SiO₂/Al₂O₃ molar ratio (S/A = 7.72, 9.62, 12.58, 17.82 and 29.67) on the crystallization behavior, microstructure, mechanical properties and machinability of glass-ceramics were investigated. The results demonstrated that the polymerization degree of the glass network decreased with the S/A ratio increasing, which further caused the decrease in glass transition temperature and crystallization temperatures. The increase in the S/A ratio promoted the precipitation of diopside, hectorite, kalsilite and tainiolite in glass-ceramics when the samples were heated at 750 °C, while inhibiting the precipitation of forsterite. For the glass-ceramics crystallized at 800 and 900 °C, the main crystalline phases transformed from diopside, forsterite, and nepheline to diopside, kalsilite, and tainiolite, with the S/A ratio increasing. As the SiO₂ gradually replaced Al₂O₃, the morphology of crystals changed from lamellar to granular, while the mean size of crystals reduced. The Vickers-Hardness values of glass-ceramics crystallized at 800 and 900 °C ascended with S/A ratio rising, and the values were above 6.30 GPa. The bending strength of most glass-ceramics is stable between 90 and 140 MPa, among which the maximum bending strength is 133.28 ± 14.81 MPa. The fracture toughness of the glass-ceramic crystallized at 800 and 900 °C declined, while that at 700 °C increased with a larger S/A ratio. Glass-ceramics after heat-treated at 900 °C with S/A ratio of 9.62 had the largest fracture toughness of 3.28 ± 0.15 MPa m^1/2. In preliminary tests of machinability, glass-ceramic after heat-treated at 900 °C with S/A ratio of 9.62 showed better results.     

Obtaining fused magnesia-alumina spinel and using it to produce magnesite-spinel roof refractories

Conclusions A method was developed for producing fused spinel which, when used in place of chromite as a component of the charge for basic refractories, yields roof products characterized by enhanced refractoriness under load, and also by low creep at elevated temperatures. This ensures high factors for the other properties. The preliminary testing of the refractories in the roofs of electric-steel melting furnaces demonstrated an increase in their wear resistance by 26–33% compared with the resistance of the currently supplied periclase-spinel refractories, which are used normally in these conditions.Translated from Ogneupory, No. 4, pp. 12–17, April, 1973.     

Evaluation of a simple batch distillation process for treating wastes from metalworking industries

A simple batch distillation process for the treatment of two types of industrial waste generated in a metalworking factory has been evaluated. Both types of waste are oil‐in‐water emulsions composed of numerous compounds and each type has a high content of water‐soluble species. The water‐soluble nature of the wastes precludes the use of conventional treatment technologies, such as ultrafiltration or chemical emulsion breaking, since they need to be complemented with additional treatment processes that would probably increase the cost considerably. A simple characterization of the liquid–vapour equilibrium and a scale‐up study has demonstrated the applicability of this technology. The process allows 90% of the waste to be recovered as water, thus achieving the required quality limits for discharge into a municipal wastewater treatment plant. An approximate estimation of capital investment and operating costs for an existing case has shown the economic viability of this process. Copyright © 2004 Society of Chemical Industry     

Perspective of the application of ash from the ceramic industry in the development of alkali-activated roof tiles

The construction industry is always in need of new technologies and products that improve technological characteristics. Alkali-activated materials appear as an alternative to reduce energy costs, improve technological properties and still present themselves as materials with the potential for incorporating industrial waste. The objective of this research was the development of roof tiles through the process of alkaline activation using ash from the kilns of burning of a red ceramic industry. After the process of processing the materials and their characterizations, prismatic specimens (115 × 30 × 20 mm) were made with the replacement of 0, 6.25, 12.5, 25 and 50% ash by metakaolin and subsequently separated into two groups, (i) subjected to curing at room temperature and (ii) subjected to curing at a temperature of 80 °C, in both cases with a curing time of 7, 14 and 28 days. After each curing period and group, the specimens were subjected to technological evaluation of water absorption, porosity, flexural strength and scanning electron microscopy. The results obtained demonstrate that the use of ash from ceramic waste, mainly replacing 12.5% of the metakaolin, promotes a reduction in water absorption and porosity, and an increase in flexural strength. The results obtained at 28 days in thermal curing are 44.05 MPa for 12.5% ash, much higher than the reference composition (16.02 MPa). The increase in strength happens due to the formation of tobermorite, due to the calcium present in the ash, and due to the formation of phases rich in potassium from the ash, such as kalsilite. Thus, it is concluded that the use of ash from ceramic waste is possible in the alkaline activation of roof tiles due to the occurrence of additional mechanisms of alkaline activation.     

Utilization of polymer wastes by joint pyrolysis with peat to produce high-calorific gas

Methods for the utilization of polymer wastes are surveyed. The results of experimental studies on the pyrolysis of peat–polyethylene mixtures depending on process conditions are reported. The yield of pyrolysis products and the composition and calorific value of gases were studied; in this case, the calorific value increased by 30–40%, as compared with the heat of combustion of gas generated from peat.     

Experimental study and optimization of the composition of heat-insulating tiles made of textile production wastes

As a result of studying the composition of heat-insulating tiles molded from textile wastes, equations were obtained which can be used to determine the acceptable percentage ratios of chemical fibres in the finished product and the necessary density of the mixture.     

Enzymatic modification of triolein: Incorporation of caproic and butyric acids to produce reduced-calorie structured lipids

Lipase-catalyzed acidolysis of triolein with caproic and butyric acids was performed to produce reduced-calorie structured lipids (SL). The SL were obtained by incubating a 1:4:4 mole ratio of triolein, caproic acid, and butyric acid, respectively, with 10% of lipase (w/w of total substrates) in 1.5 mL hexane at 55°C for 24 h. Of nine commercially avaialble lipases screened, IM60, which contains the lipase from Rhizomucor miehei, was the most effective and produced 13 mol% unreacted triolein, 49% disubstituted, and 38% monosubstituted triacylglycerols that contained short-chain fatty acids. The products were analyzed by reverse-phase high performance liquid chromatography with an evaporative light-scattering detector. Reaction parameters studied included time course, temperature, enzyme load, and substrate mole ratio. The yields obtained demonstrate that a structured lipid with long-chain and short-chain fatty acids can be synthesized by using IM60 lipase in organic medium.     

Incorporation of indolinospirooxazine on ethylene-vinyl acetate copolymer to produce a intelligently temperature-regulated nonwhite cool material

Cool materials that adjust cooling efficiency according to sunlight intensity are needed because people have different needs for cooling at different times. Several colors of commercial microencapsulated photochromic powder were melt blended with ethylene-vinyl acetate copolymer in a two-roll mill at 90 °C to prepare the photochromic films of corresponding colors. Pink photochromic films [the organic photochromic compound is indolinospirooxazine (NISO)] were selected to continue the following variable experiment due to its best performance in the indoor cooling test. The pink photochromic films change color as well as transmittance according to the intensity of sunlight, thereby achieving an intelligent cooling effect. A maximum decrease around 10 °C was observed in natural environment when the addition amount of pink photochromic powder reaches 2.0 phr under strong sunlight and all films did not show cooling effect under weak sunlight. This material can be covered on buildings to regulate the indoor temperature. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48887.     

Nitric acid acidulation of phosphate rock and pyrolysis of acidulate to produce phosphatic and nitrogen fertilizers

A modified method for producing a range of dicalcium phosphate containing phosphatic fertilizers and aqueous calcium nitrate is discussed. The process consists of reacting phosphate rock with nitric acid followed by pyrolysis of the resulting acidulate to produce dicalcium phosphate (CaHPO₄) and to liberate approximately one-half of the initially consumed nitric acid. Recycling of the liberated nitric acid allows production of available phosphate at approximately one-half the acid equivalents consumption normally utilized in wet-process acid production. The calcium nitrate by-product is separated from the phosphatic component of the pyrolyzate by dissolution in water followed by filtration. The initial HNO₃ : CaO acidulation ratio governs the available P₂O₅ content of the phosphatic fertilizer, which may be as high as 47%. The aqueous calcium nitrate stream may be processed to produce a variety of solid or fluid nitrogen fertilizer products. No throwaway by-products (other than possibly siliceous gangue) are produced. Estimates are given for raw materials needed and energy cost.     

2004-2005年国外环氧树脂工业进展

综述了2004-2005年国外环氧树脂工业原料供应、价格变动、公司收购、投资建设等方面情况,并对树脂、固化剂、粘接剂、复合材料等领域的新产品、新技术作了介绍。     

Potential use of Kraft pulp mill and flat glass cutting wastes in red ceramic products

This study assessed the incorporation of green liquor dregs, an inorganic solid waste from Kraft pulp mill, and flat glass cutting waste (FGCW) into red ceramic formulations. Since in Brazil sanitary landfills are still the main destination of industrial wastes such as those used in this research, a survey was conducted to identify the number of landfills in the region of origin of each waste and the amount of waste that could have this destination avoided. The effects of firing temperature and simultaneous incorporation of both industrial wastes were analyzed to optimize heat treatment and waste content in the formulation to manufacture red ceramic products. The influence of green liquor dregs and FGCW incorporation into clayey mass was evaluated varying waste content between 0 and 50 wt%. The specimens were prepared by uniaxial pressing, fired at 850 and 950 °C, and had their physical-mechanical properties and mineralogical and microstructural characteristics analyzed. The best results were obtained for the formulation with 10 wt% green liquor dregs and 30 wt% FGCW fired at 950 °C. This result highlights the potential of using green liquor dregs, a waste difficult to be recycled due to its chemical composition, associated with FGCW, which acts as a fluxing agent in ceramic formulations.     

Carbon mineralization from composts and food industry wastes added to soil

We have studied the short term C mineralization of six wastes from important food industries, one sludge from a biogas plant and three composts. All the wastes were characterized chemically and fractionated according to the Van Soest method. The fresh wastes were incubated under controlled environment conditions to determine the C mineralization rate. Based on first order mineralization kinetics, we calculated the hypothetical amount of stable C in the wastes as the amount of C that would not be mineralized within one year under field conditions. The percentage of stable organic C in the organic matter was in general much larger in the composts than in the other wastes, but when expressed on dry matter, the non-composted wastes had comparable or larger amounts of stable organic C than the composts and have a considerable potential for supplying organic matter to soils, and hence for C sequestration. The amount of stable organic C could best be predicted by the total N content of the wastes (R _a ² = 0.855), whereas the results of the fractionation had very little predictive power, probably due to problems related to the high ash content of some of the wastes. An index that combined stable organic C and N and P content in the wastes was calculated to assess possible limitations for applying these wastes in agriculture. Under current nutrient legislation in Western Europe, a number of these wastes will only be usable in small amounts, but these and other food industry wastes could still prove to be valuable soil amendments in nutrient poor situations, for increasing soil organic C content and supplying nutrients.