Use of nonconventional raw materials in ceramic production

This paper reports possibilities for use of nonconventional natural and synthetic raw materials in ceramic bodies and glazes.

Reactivity during the process of heating can be considered as a modern criterion for ceramic raw materials. A review of several types of alkali-containing rocks is made, which are more fusible than the common fluxes. The greater fluxing power of these raw materials compared to the traditional types provides for a higher rate of body sintering. As a result of this intensified process, a higher structural density and better mechanical strength of the bodies are achieved with shortened firing cycles. The introduction of more active fluxes reduces firing costs and allows economy of high quality traditional fluxing raw materials in the production of some tablewares, sanitary wares and faience tiles.

In combination with more reactive silicon-containing raw materials, the influence of the fluxes on sintering increases. This combined beneficial effect is experimentally confirmed in glaze frit melting and in the firing of glaze coatings. Investigations on these processes are discussed.

As a nonconventional raw material in the modern ceramic production, wollastonite can be considered. Since natural deposits of this valuable material are rarely found the use of synthetic wollastine is discussed. Obtaining an anorthite reaction phase in the ceramic bodies provides the formation of a compact and stable structure that permits firing in short and single cycle.     

Reuse of glass waste in the manufacture of ceramic tableware glazes

Today, various studies are carried out to spread the understanding of sustainability. The sustainability of production processes gains importance in corporate areas. In this study, the use of glass waste instead of frit used in glaze compositions in the ceramic industry was evaluated. The chemical and physical properties of glass wastes on samples were examined. The glaze formulations were prepared using 3%, 5%, and 8% by weight of glass waste instead of frit. Glass wastes were added to glaze compositions and 12 different glaze formulation studies were carried out. Transparent, Opaque, and Matte test glazes were prepared with glass waste added glaze formulations, and these glazes were applied to ceramic bodies. SEM (scanning electron microscope) analysis of standard glaze and glass waste added glazes was performed to determine the microstructural and morphological characterizations. Also, surface whiteness, brightness, L*a*b values, glaze flows, harcort test results, and final water absorption values were compared. As a result of the studies, it has been determined that it is appropriate to use 3% glass waste by weight instead of the frit in the production of ceramic tableware.     

Application of sewage sludge in the manufacturing of ceramic tile bodies

The substitution of clayey raw materials urban sewage sludge in the production of traditional ceramics could give place to a cost saving due to the utilisation of wastes as secondary raw material. At the same time, it can help to solve the environmental problems associated to such wastes. This research shows the results of the substitution of clay for sewage sludge in different proportions in a ceramic body. The sludge characterisation has been carried out by an analytical protocol. After that, the most suitable products were selected regarding to the chemical composition and the technological characterisation of the resulting ceramic material.     

我国制磷电炉炉渣的综合利用

分析制磷炉渣的特性,介绍磷渣综合利用途径:制水泥掺合料,作硅肥,生产白炭黑,生产保温材料、炉渣砖、釉面瓷砖,制SU F微细粉等,并对磷炉渣的利用提出了几点建议。     

Refractory coatings based on nonferrous metallurgy waste products

Use of salt waste products from secondary processing of aluminum-containing slags and scrap calcined at 950°C are used to prepare a refractory coating (unmolded refractory). This expands considerably the raw material base for refractory material production, and makes it possible to utilize industrial waste products.     

Development of TiO2 white glazes for ceramic tiles

The objective of this work was the use of titania polymorphs (rutile and anatase) in substitution of zirconia as the main component for producing white opacity in ceramic glazes for tile coatings. Initially, total zirconia (12% mass fraction) was replaced in the standard frit by rutile and by anatase in mass fractions of 5%, 10% and 15%, forming two frit groups processed as ceramic glazes. The glaze color was determined by spectrophotometry and the glaze microstructure by XRD and SEM. The results showed the frit containing 10% anatase formed a totally white glaze presenting excellent coating capacity. The frits containing rutile produced yellow opacity. The results of microscopy and X-rays diffraction revealed that opacity was caused by tiny rutile crystals in the anatase frits and by titanite crystals in the rutile frits.     

活性陶瓷滤料过滤器在高浊度含油水处理中的应用

针对高浊度含微量油原水,采用活性陶瓷滤料过滤器替代传统的多介质过滤器和活性炭过滤器作为化水制水预处理工艺。对活性陶瓷滤料的特性和过滤原理、活性陶瓷滤料过滤器系统组成进行了介绍,结合某钢厂化水站采用中水作为水源水制备锅炉补充水的工程实例,对活性陶瓷滤料过滤器的运行效果进行了分析。     

Low-cost ceramic membranes: A research opportunity for industrial application

Obtaining low-cost ceramic membranes has attracted great interest in the scientific community in last years, as it allows to preserve the advantages of ceramic materials while significantly reduce their manufacturing costs. This type of membranes is mainly based on the use of raw materials and manufacturing processes typical of traditional ceramic materials, i.e silicate-based ceramics. This work exhaustively reviews the raw materials, ceramic compositions and variables of the manufacturing processes used in the development of these membranes, with special emphasis on their numerous potential industrial applications.     

The use of sewage sludge and marble residues in the manufacture of ceramic tile bodies

The substitution of clayey raw materials for other wastes, in this case urban sewage sludge and marble sludge, in the production of traditional ceramics could be cost effective from the utilisation and recycling of these wastes as a secondary raw material. At the same time, it can be helpful in tempering the environmental problems associated with such wastes. This research shows the results of the addition of marble sludge and urban sewage sludge in different proportions to clay in a ceramic body. The most suitable products were selected regarding the mineralogical composition of the resulting ceramic material and its technological behaviour. To evaluate the ceramic properties of the obtained material, several processing and product properties (linear contraction, water absorption, bending strength) were determined. With regard to the technological properties of the final ceramic bodies, there does not seem to be any clear relation between the linear contraction values and the content of residue. However, the increase in water absorption along with the increase in the residue content is evident. The addition of residue decreased the bending strength. The selection of the adequate content of sludge to be added to the ceramic body will be controlled by the usual standards applied to construction materials.     

Minimization of Pb content in a ceramic glaze by reformulation the composition with secondary raw materials

In this study a commercial ceramic glaze composed by both olivine (magnesium iron silicate, (Mg,Fe)₂SiO₄) and commercial frits, rich in lead (about 30 wt%), was reformulated by using secondary raw materials (CRT cone glass and municipal solid incinerator post-treatment bottom ashes before and after vitrification). The waste-based products were characterized and, compared to the standard glaze, showed better acid resistance, comparable aesthetic characteristics and slightly lower stainless resistance. Environmental benefits were obtained by saving natural raw material (olivine), by reducing lead percentage in the proposed formulations (from around 30 to 5 wt%), by energy saving (for the avoided use of commercial frits) and by reducing lead content in the new compositions.     

Thermochemical Treatment--Technologies for Recovery and Utilisation of Materials

The arc furnace technology is an ideally suited process for the treatment of hazardous and problematic waste. The operation conditions of the arc furnace can be adapted for optimal transformation of the waste material input into raw materials and usable products. The process can significantly reduce the impact of contaminated wastes and industrial residues, and enable material conversion and separation. Thus, the products of the process have various applications. The capability of the process is illustrated with three examples, the treatment of bottom ash and filter ash from waste incineration plants, of stainless steel slags and of chromium containing residues from the refractory industry.     

Cathode-Ray Tube panel glass replaces frit in transparent glazes for ceramic tiles

The disposal of Cathode Ray Tubes (CRT) from end-of-life personal computers and TV screens represents a serious problem in electronic-waste management. As an assembly of different materials, finding a use for each of a monitor's parts is a critical step forward a solution. However, the CRT panel is a silicate glass with a relatively high proportion of alkaline and alkaline-earth oxides, for which recycling is a natural task, and the replacement of frit in ceramic glazes arises as an interesting alternative. In this context, we investigated the effect of CRT panel glass in glazes for ceramic tiles based on a comparative analysis. We replaced up to 40?wt% of commercial transparent frit with CRT panel glass in the formulation of one reference slurry. Chemical analyses were conducted by X-ray fluorescence (XRF) and inductively coupled plasma optical emission (ICP-OES) spectrometry. The thermal expansion coefficient and the glass transition and dilatometric softening temperatures were characterized by dilatometry and compared to such properties calculated as a function of composition, using the SciGlass software and database. 20- and 30-min firing cycles were applied in a fast-firing roller kiln, replicating industrial conditions. The samples transparency was measured by spectrophotometry and compared to the colorimetric parameters of a standard glaze. The maximum content of panel glass possible to add in the transparent glaze formulation without affecting the expected properties was 20?wt%, above which transparency decreased due to heterogeneities. The reformulation of a ceramic glaze with waste CRT panel glass was successful, thus suggesting an interesting approach for disposal of other electronic wastes.     

Fe—Mn—Cr—Ni系黑色料制备工艺的研究

以废钢渣为主要原料，添加部分化工原料，制备出了Ｆｅ－Ｍｎ－Ｃｒ－Ｎｉ系无钴黑色料。采用现代测试技术对其最佳制备工艺及基础釉的应用性进行了检测。结果表明，在确定料合成温度后，废钢渣的预处理及色料的粒度对色料的呈色影响显著，此系色料不适应于锌釉和镁釉。     

Zircon-free frits suitable for single fast-firing opaque wall tile glazes and their industrial productions

Wall tile glazes with a smooth surface texture, high glossiness, and whiteness are usually based on zirconium containing frits. However, these frits are quite expensive and therefore, there have recently been certain attempts to lower the production cost such as taking suitable glass–ceramic glaze systems into an account. With the present work, the frit-based glaze compositions belonging to the K₂O–MgO–CaO–ZnO–Al₂O₃–B₂O₃–SiO₂ glass–ceramic system were studied to prepare newly synthesized wall tile glazes for industrial single fast-firing. The design of a glass–ceramic glaze for this type of tiles should ensure that the selected frit precursor is technically and commercially compatible with the manufacturing conditions generally used in the production of glazed ceramic wall tiles. The aim of the study is to develop zircon-free, frit-based, glossy opaque glass–ceramic glazes for wall tiles by optimizing the CaO/MgO and adjusting the Al₂O₃/alkali ratios in the starting frit compositions. Frit production, glaze preparation, application, and single fast-firing of wall tiles were, first of all, conducted under laboratory working conditions and then, successful recipes were adapted to the relevant industry. The frit crystallization capability and crystallization temperature range were determined by differential thermal analysis (DTA). Thermal expansion coefficient values of glazes were determined by a dilatometer. Characterization of single fast-fired glass–ceramic glazes was made by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) techniques. Colour and gloss analyses of the final glazes were measured with a spectrophotometer and a gloss meter, respectively.     

Evaluation of solid wastes in the manufacture of ceramic tableware glazes

The recovery and reuse of industrial wastes are of great importance to the environment. Today, a large amount of waste is produced due to marble production, and it is extremely important to bring such wastes to the ceramic industry, to solve the pollution problem and to provide cost-efficient ceramic production. In this study, marble waste was used for ceramic earthenware glaze and body formulations. Marble waste was used in two different formulations as glaze and body. Chemical analysis, morphological features, crystallographic information of different formulations were made with XRF, SEM and XRD, respectively. When the hardness test results of the ceramic body and glazed samples were examined, the hardness values of the marble waste added samples increased by 1.9% compared to the standard samples. According to the results obtained, it has been seen that using marble waste in the ceramic industry is very important for both economic and environmental reasons.     

建筑陶瓷装饰技术的现状和展望

建筑陶瓷制品竞争的一个重要方面是花色品种的竞争,竞争的焦点是产品设计和装饰材料的水平。装饰材料包括陶瓷颜料、熔块、干粒、液体色料、渗花釉等。其中,不乏一些新型陶瓷装饰材料如仿金属色料、相干色料、仿金属釉、虹彩釉、反应釉、各种熔块、干粒等,在装饰手法上吸收了很多日用陶瓷和艺术陶瓷的装饰手法和印刷行业的惯用技法如手彩、釉中、釉下彩,丝网印花、辊筒印花、喷墨印刷等。我国要缩小建筑陶瓷制品和国外先进国家的差距,首当其冲的是要在产品的装饰材料、装饰技术上迎头赶上;不仅要缩短两者在硬件方面的差距,还要缩短在软件方面的差距,使我国建筑陶瓷产品的档次有明显的提高。     

磷矿渣用于陶瓷坯料试验研究

磷矿渣作为工业废料,其合理利用极具经济价值,根据其组成特点,适当配合其它原料,经试验证明,完全可以用于陶瓷产品的坯料配制,再配以高强乳浊釉对有色坯体进行有效的遮盖,则可以生产出各项性能指标符合要求的釉面砖制品。     

Anorthite-based transparent glass-ceramic glaze for ceramic tiles: Preparation and crystallization mechanism

A series of high hardness anorthite-based transparent glass-ceramic glaze was successfully developed for ceramic tiles. These glazes were prepared by mixing a high-calcium frit (denoted as HCa) that can crystallize anorthite with other fluxes. The effect of HCa content on the crystalline phase, microstructure and properties of the glaze was studied. In addition, the phase transformation, microstructure evolution and crystallization kinetics of anorthite from frit glaze were investigated in detail. The results revealed that when the HCa content was 45–55 wt%, the glazes had excellent transparency with a hardness of 6.4–7.3 GPa, which was higher than conventional glazes. The XRD and SEM tests showed the crystallization of single-phase lamellar-shaped anorthite crystals up to 20–40 μm in length. Anorthite was found to crystallize directly from the frit glaze at 850 °C. The laminated anorthite was composed of thinner lamellae, and cracks were observed inside the large crystals. The activation energy of anorthite crystallization was about 420 kJ/mol, and the Avrami index (n) was 2.03?2.36. The n value indicates that the crystal is grown in two dimensions, which explains the formation of lamellar-shaped anorthite in SEM.     

低成本一次低温快烧生料无光釉的研制

以工业废渣为主要原料研制了低温一次快烧生料无光釉，分析探讨了废渣无光釉的化学组成和烧成条件，该釉不仅适于一次低温快烧工艺，而且可显著降低釉料成本，在墙地砖生产中有较大应用价值。     

硅渣制九水偏硅酸钠工艺研究

九水偏硅酸钠作为碱水剂广泛用于陶瓷工业生产中。通过利用冰晶石生产过程中产生硅渣与片碱生产九水偏硅酸钠和天然石英石与液碱生产九水偏硅酸钠的两种生产工艺进行研究和对比,指出用工业硅渣代替石英石生产九水偏硅酸钠具有成本和环保优势。