Optimization of wastes content in ceramic tiles using statistical design of mixture experiments

Mineral extraction and processing industries have been cited as sources of environmental contamination and pollution. The inclusion of wastes into productive cycles represents an alternative form of restoration, which is interesting from both environmental and economic standpoints. In this work, the development of ceramic tile formulations containing kaolin processing and granite sawing wastes was investigated using the statistical design of mixture experiments methodology. Ten formulations using the raw materials, red clay, kaolin processing and granite sawing wastes, were selected and used in the mixture design. Test specimens were fired and characterized to determine their water absorption, linear firing shrinkage and modulus of rupture. Regression models were calculated, correlating the properties with the composition. The significance and validity of the models were confirmed by statistical analysis and verification experiments. The regression models were used to optimize the waste content in ceramic compositions. The results showed that formulations containing up to 62% of waste could be used in the production of ceramic tiles.     

Untreated coffee husk ashes used as flux in ceramic tiles

The agro-industrial activities are responsible for the production of large amounts of solid wastes, which, so far, have found scarce reuse alternatives. Among the former, coffee bean beneficiation generates an equal amount of coffee husks whose highest reuse potential is as fuel. The resulting ashes are frequently an object of illegal covert disposal and a serious source of environmental impact. However, coffee husk ashes (CHA) are particularly rich in alkaline and alkaline-earth metals, and might be adequate to replace the traditional feldspars, which are used in high content as fluxes in clay-based ceramic formulations but are becoming scarce and costly. In this work, the fluxing effect of CHA additions to an industrial clay-based mixture was evaluated. Based on the characterization results and the mullite–silica–leucite phase diagram, additions of 5 to 20 wt.% CHA were made to the clay-based mixture and the resulting compositions were evaluated after sintering at temperatures between 1100 and 1200 °C (60 min soaking time). The results obtained show that firing temperatures near 1180 °C and ~ 10 wt.% CHA addition lead to linear shrinkage, water absorption and flexural strength values that fall within the range specified by floor tile standards (NBR 13817, EN 176 and ISO 13006), requiring no significant changes in processing parameters. Coffee husk ashes can thus advantageously replace feldspars in the role of fluxing material, with the potential to reduce not only natural ceramic raw material consumption, but also production and landfill costs as well as waste disposal area requirements.     

The effects of fine fire clay sanitaryware wastes on ceramic wall tiles

In the last decade, environmental preservation has become an important issue. Specifically, recycling of sanitaryware fine fire clay (FFC) waste is important for reducing costs. In this study, the use of FFC waste as an alternative raw material in the production of ceramic wall tiles was investigated. Five ceramic wall tile bodies were prepared by substituting kaolin (max. 15 wt%) with FFC wastes. All formulations were mixed, pressed into pellets and sintered at 1145 °C. The sintering behaviour was evaluated using an optical dilatometer. Water absorption, linear shrinkage and bending strength were also measured. This study revealed that FFC wastes are good alternative raw materials, and the corresponding formulations were shown to be viable in the manufacturing of ceramic tiles. The most remarkable conclusion from this study was that the addition of FFC waste decreased moisture expansion.     

中国水泥工业消纳社会废弃物与发达国家的差距

预分解水泥窑消纳各种含有可燃质的废物,既可充分利用其残留的热值,还能彻底干净地处置其燃烧后的残渣,消除二次污染隐患;加之水泥窑适应范围广,可以消纳各种状态的废料,处置能力很大。此法比新建垃圾填埋场或焚烧厂等办法经济得多,收效更快。水泥工业还可以将各种工业废渣用作混合材掺于水泥熟料中一并粉磨成水泥;有的工业废料还可以用作水泥原料以替代天然的石灰石、粘土或铁矿石等。在水泥工业消纳社会废弃物方面,我国与德日美等发达国家,在理念和技术上还有差距：我国看似消纳混合材不少,实为部分超掺滥掺所致;我国原料和石膏的替代率尚有较大提升空间;我国替代燃料的应用十分滞后,须急起直追。     

Recycling of industrial wastes in ceramic manufacturing: State of art and glass case studies

Nowadays, ceramic tile are manufactured at zero emissions permitting to recycle all by-products and part of residues derived from depuration treatments (exhausted lime, glazing sludge and polishing sludge). In addition to this environmentally friendly tendency, in the last years an increasing number of scientific studies demonstrated the feasibility to use alternative raw materials in substitution of different component of the ternary clay-feldspar-quartz system. In the first part of the paper is reported the state of the art of industrial waste recycling in the ceramic sector, with the focus on review studies related to both ceramic tiles and bricks..In the second part of the work are reported two case studies conducted by the authors with the aim to formulate ceramic bodies using alternative raw materials. New tailored compositions were obtained replacing clays, flux and/or inert compounds (higher than 60 wt%) by scraps from packaging waste glass in tiles, and cathode ray tube glasses and packaging waste glass up to 20 wt% in the brick compositions.     

Amorphous silica wastes for reusing in highly porous ceramics

The paper analyzes a solution in green manufacturing of foamed or cellular ceramics. The objective of this study was to determine the technical solution for rice husk ash and “tales” of mixed glass cullet reusing based on the specific properties of these materials for creation of spherical holes inside ceramic using the process of coalescence of cellular glass. The paper reports on experimental results obtained from the production of lightweight cellular glass granules produced using glass cullet and rice husk ash. Lightweight cellular glass granules were mixed with clay, pressed and fired in air at 920°C. Clay sintering and the formation of ceramic were followed with the coalescence of cellular structure of glass granules and with the formation of spherical hollows inside the matrix. Density and strength of the fired ceramic bodies were determined. It is observed that the lightweight ceramics with density 900 ÷ 920 kg/m³ possess a compressive strength of about 5 MPa that is acceptable for bricks or tiles manufacture. The utilization of amorphous silica waste for lightweight ceramics manufacture helps in reducing waste disposal concerns and costs associated, and also transforms the waste into an alternative raw material with added value, moreover making the final product cheap.     

利用工业废料研制再生陶瓷初探

为了材料的充分循环,实现可持续发展,研究人员对回收工业废料用做陶瓷原料的技术进行了探索。本文阐述了再生陶瓷的研发状况,介绍了其粉体制备、坯料、配方、成型和烧成工艺,同时还针对节能环保的要求,研究了降低烧成温度和缩短烧成周期的策略。回收废瓷粉、废玻璃粉、燃烧灰烬、废粘土、废赤泥(氧化铝工业废料)和粉煤灰等工业废渣,配成多种陶瓷坯料,并测试了各种坯料配方的物理特性,确定了每种配方的烧成温度。配方中添加废玻璃可以有效地降低烧成温度。研制出的一种再生陶瓷的可行性坯料配方是:80-20%废瓷粉,20-80%燃烧灰烬,30%废玻璃粉。坯料干压成型,经1100℃烧成后,吸水率为9.9%,体积密度为2.52g/cm3。该坯料配方可采用速烧工艺。     

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.     

Utilization of muscovite granite waste in the manufacture of ceramic tiles

Granite waste is by-product from a decorative rock industry. The present study aims to investigate the effect of muscovite granite waste on the physico-mechanical properties of ceramic tiles to demonstrate its suitability for industrial production. A series of flooring- and facing ceramic tiles were prepared by adding 20, 25, and 30 wt% muscovite granite waste into the batch compositions. The sintering behavior and degrees of densification of two kinds of ceramic tiles were evaluated by determining their physico-mechanical properties and characterizing them by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. As expected, the facing ceramic tile (FacCT1) sample, containing wollastonite, hematite, anorthite, quartz, and cristobalite, with 20 wt% muscovite granite waste showed lower physico-mechanical properties than those of the flooring ceramic tile (FloCT3) sample, containing mullite, calcium aluminosilicate, quartz, and cristobalite, with 30 wt% muscovite granite waste. The reason is that lower firing temperatures cannot accelerate a complete fusion of the granite waste which behaves like an inert non-plastic material similar to quartz. These results illustrate the prospects of utilizing muscovite granite waste in ceramic tile production.     

水泥窑处理工业废物的工厂实验研究

Destruction of industrial waste in cement rotary kilins(CRKs) is an alternative technology for the treatment of certain types of industrial waste(IW).In this paper,three typical types of industrial wastes were co-incinerated in the CRK at Beijing Cement Plant to determine the effects of waste disposal(especially solid waste disposal )on the quality of clinker and the concentration of pollutants in air emission.Experimental results show that(1) waste disposal does not affect the quality of clinker and fly ash,and fly ash after the IW disposal can still be used in the cement production,(2) heavy metals from IW are immobilized and stabilized in the clinker and cement,and (3) concentration of pollutants in air emission is far below than the permitted values in the China National Standard-Air Pollutants Emission Standard(GB 16297-1996).     

Integrated utilization of high alumina fly ash for synthesis of foam glass ceramic

Due to the numerous increase of the building energy consumption and huge volume of industrial wastes produced in China, the development of thermal insulation materials is quite needed. Herein, foam glass ceramic, a kind of thermal insulation materials, was fabricated by using solid wastes high alumina fly ash and waste glass as the main raw materials. First, in this study the proportion scheme of this research was designed by using Factsage 7.1 and the foaming agent was CaSO₄. Secondly, the decomposition of calcium sulfate and the influence of process parameters, namely the sintering temperature and the foaming agent additive amount, on the microstructure and mechanical properties of foam glass ceramic were investigated. The experimental results showed that when the proposed foam glass ceramic was sintered at between 1180 and 1220?°C, it exerted excellent macro and micro properties. The optimum parameters were 2% CaSO₄ addition and sintering temperature of 1200?°C, and the corresponding bulk density and compress strength values were 0.98?g/cm³ and 9.84?MPa, respectively. Overall these results indicated that the preparation of foam glass ceramic made up a promising strategy for recycling industrial waste into new kind of building insulation materials.     

Zukunftssichere und umweltneutrale Beseitigung von Industrieabfällen

Low environmental-impact disposal of solid, liquid and semisolid industrial residues . In many production plants, waste residues are formed which must be treated before their disposal so as to safeguard against environmental pollution. Industrial methods for the treatment and disposal of residues are so multifarious that each disposal problem requires careful consideration so as to ensure selection of the most suitable method, both from the ecological and economical point of view. Dumping grounds cannot accommodate all waste materials without endangering or disturbing the environment. For incineration, proven methods are available which can be modified to suit the particular waste problem at hand. After a suitable pretreatment every effort must be made to achieve a waste free from organic materials, an optimum utilization of heat and a flue gas purification without inadmissible loading of waste gases and waters. In recent years there has been a considerable increase in research and development activities in the area of thermal treatment of solid, liquid and semi-solid wastes. Worth mentioning are the high-temperature methods giving favourable emission values and methods for degasification and gasification directed at the recovery of important raw materials. Plants based on these principles are currently being operated on the pilot scale.     

利用粉煤灰等工业废料制备日用陶瓷的研究

针对目前火电厂大量排放粉煤灰,陶瓷工业产生大量废匣钵、废瓷粉但得不到充分利用的现象,为了使其变废为宝,本实验在长城陶瓷有限公司成熟的注浆泥配方的基础上,利用正交实验设计配方,经调整配方组成,加入了粉煤灰等工业废料,现己研制出清洁生产日用陶瓷的配方。其中粉煤灰、废匣钵、废瓷粉的含量分别是10%,10%,8%,工业废料的含量合计达到了28%。由于粉煤灰、废瓷粉和废匣钵的价格低廉,应用此技术则可以为企业带来可观的经济效益。     

Recycling of granite waste and burnt coal cinder for the preparation of sintered permeable bricks

The sintered permeable brick was prepared using granite waste and burnt coal cinder (BCC) as raw materials to ensure the utmost utilization of both solid wastes. The effect of various parameters, such as the proportion of raw materials, granite particle size and sintering temperatures on the properties of the permeable brick were studied, and the relevant sintering mechanism was clarified. The differential scanning calorimetry curves indicate that the mixture of granite waste and BCC begins to melt at a lower temperature, which is lower than the temperature for melting them alone, so the use of them to prepare sintered bricks will reduce energy consumption. The optimal conditions for the preparation of the permeable bricks were determined as the mass ratio of granite waste to BCC of 80: 20, sintering temperature of 1150–1175°C, and granite particle size of .9–1.25 mm. It was found that the permeability and the flexural strength of the samples can reach 3.41 × 10 ⁻² cm/s and 4.2 MPa, respectively, which both exceed the requirements specified in the national standard of China.     

Optimization of pelletisation and combustion in a boiler of 17.5 kWth for vine shoots and industrial cork residue

Wood pellets have become an important renewable energy fuel. Nowadays the main raw materials used for their production are wood wastes from wood industries. However, these wood wastes have other uses in Spain and it is necessary to look for other possible raw materials. In this work, vine shoots and industrial cork residue were studied as raw materials. The results showed that pelletisation of vine shoots presented a high energy demand. This energy requirement was reduced with the addition of industrial cork residue. Moreover, industrial cork residue decreased the ash content of pellets and increased their heating value, although it decreased their physical properties at the same time. Regarding combustion, the addition of industrial cork residue decreased the accumulation of ash in the pellet burner and its sintering tendency. The major conclusion of the work is that the most appropriate blend to improve pelletisation and combustion processes is 30% wt. of vine shoots and 70% wt. of industrial cork residue.     

废瓷掺料对微晶玻璃熔融结晶的影响

利用瓷土尾矿、废瓷、粉煤灰等工业废料作为主要原料制备微晶玻璃,不仅能够有效解决工业废弃物的环境污染问题,而且能够实现废弃物的资源化利用。在配方设计中,瓷土尾矿、粉煤灰等固体废料的用量可达原料总量的75%以上。但废瓷粉的掺入会破坏微晶玻璃表层的析晶效果,由于废瓷的种类繁多,其化学组成、所含杂质及烧结温度具有很大的差异性,会对微晶玻璃的熔融结晶产生较大影响。     

Synthesis of a foam ceramic based on ceramic tile polishing waste using SiC as foaming agent

Due to the large amount of ceramic tile polishing waste generated in China, the recycling of this waste residue becomes important. Herein a foam ceramic was successfully produced by using ceramic tile polishing waste as main raw material. In this research, SiC was added as the foam agent, and the foaming mechanism was also investigated. The results showed that the best dosage of SiC was 1%. Furthermore, in order to obtain a foam ceramic with better structure, the sodium phosphate was added in raw materials as foam stabilizer. The influence of this addition on the microstructure and properties of foam ceramic was investigated. It was found that the optimum additive amount of sodium phosphate is 2–3%.     

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.     

陶瓷抛光废料对多孔陶瓷砖气孔形成过程影响的研究

本文以陶瓷抛光废料为主要原料,研制了以石英和莫来石为主晶相的多孔陶瓷轻质砖,采用XRD、显微镜分析了陶瓷抛光砖废料对其气孔形成过程的影响,探讨了影响其气孔形成的主要因素。研究结果表明,陶瓷抛光砖废料由于含有机物和无机盐,可作为成孔剂,在400-700℃温度范围,有机物分解形成小气孔,随着温度的升高,以钙镁碳酸盐为主的无机盐在900℃左右分解,所形成的气孔由小变大;影响多孔陶瓷轻质砖气孔形成的主要因素是原料配方和烧成制度。     

抛光砖废渣制备轻质外墙砖工艺参数的研究

采用抛光砖废渣等工业废渣为主要原料,以高可塑性粘土、黑滑石、钾长石、石英和煅烧氧化铝为辅助原料制备陶瓷轻质外墙砖,研究了抛光砖废渣用量、成型压力以及烧成制度对轻质外墙砖性能和质量的影响。结果表明：随着抛光砖废渣用量增加或成型压力的降低,轻质外墙砖的导热系数提高而抗压强度与容重则降低。通过TG-DSC分析确定了在小于等于...