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By J. A. Voigt

In an effort to determine the optimum conditions for preparing high purity, fine particle size high temperature superconducting oxide powder, we have investigated how calcination conditions influence the conversion of a chemically prepared hydroxycarbonate precursor powder to YBa2Cu307. We find that the precursor can be converted to phase pure YBa2Cu307 in either oxygen or synthetic air (20% 02. 80% N2) at 850°C. This temperature is substantially lower than the temperature (>900°C) normally used for the calcination of mixed-oxide powders. The lower calcination temperature prevents particle sintering and maintains the desired fine particle size. Powder processed in synthetic air shows a low degree of crystallinity indicating it may be more sinterable than the highly crystalline powders produced when an oxygen atmosphere is used. Intimate contact between powder particle surfaces and a flowing gas atmosphere promotes the reaction between the BaCO3 component of the precursor powder and the Y and Cu constituents.

Jan 1, 1989

By Christian Ludwig, Virginie Silberstein, Rizlan Bernier-Latmani, Simona Regenspurg

"Residues from waste incineration (bottom ashes) form large amounts of heavy metal-rich waste. Theoretically, heating and the addition of chloride to the ashes could remove these metals by formation of volatile metal chlorides. The remaining heavy metal-poor ashes could be used, for example, as cement additives. In the proposed process of our study we used bypass dust from the cement industry as chloride additives to the bottom ashes. We aim to determine experimentally the optimal conditions to remove heavy metals from ashes and to simulate this process by thermo- chemical modeling. In our experiment we investigate heavy metal flows by heating of differently composed mixtures of bottoms ash and bypass dust in dependence of different furnace temperatures (500-1200 °C). Furthermore, we investigate the reactivity (leaching characteristic) of the resulting product in order to predict if secondary residues can be landfilled in agreement to Swiss regulations for inert materials.IntroductionThe incineration of garbage is generally considered as the most environmentally friendly method for the reduction of municipal solid waste. This is because, compared to traditional storage of waste on landfills, incineration produces less greenhouse gases and destroys toxic organic compounds. The released exothermic energy can be recuperated and the residues from the combustion chamber (bottom ash) are strongly reduced in volume. However, they still form about 600 kt of waste per year in Switzerland, which needs to be landfilled. However, these residues could be potentially used as construction materials after mechanically recovering ferrous and non-ferrous metals. However, the resulting ashes (discharged dry or wet) still contain increased amount of heavy metals (exceeding state regulation) requiring them to be finally deposed on a hazardous waste site. A thermal treatment of these ashes could enable both, to separate and recuperate the remaining heavy metals and an inorganic heavy-metal poor material. The evaporation of metals depends on temperature and can be lowered by addition of chlorides, which would lower the boiling point of most metals by formation of metal chlorides (table 1). 745"

Jan 1, 2008

By Christian Ludwig, Virginie Silberstein, Rizlan Bernier-Latmani, Simona Regenspurg

"Residues from waste incineration (bottom ashes) form large amounts of heavy metal-rich waste. Theoretically, heating and the addition of chloride to the ashes could remove these metals by formation of volatile metal chlorides. The remaining heavy metal-poor ashes could be used, for example, as cement additives. In the proposed process of our study we used bypass dust from the cement industry as chloride additives to the bottom ashes. We aim to determine experimentally the optimal conditions to remove heavy metals from ashes and to simulate this process by thermo- chemical modeling. In our experiment we investigate heavy metal flows by heating of differently composed mixtures of bottoms ash and bypass dust in dependence of different furnace temperatures (500-1200 °C). Furthermore, we investigate the reactivity (leaching characteristic) of the resulting product in order to predict if secondary residues can be landfilled in agreement to Swiss regulations for inert materials.IntroductionThe incineration of garbage is generally considered as the most environmentally friendly method for the reduction of municipal solid waste. This is because, compared to traditional storage of waste on landfills, incineration produces less greenhouse gases and destroys toxic organic compounds. The released exothermic energy can be recuperated and the residues from the combustion chamber (bottom ash) are strongly reduced in volume. However, they still form about 600 kt of waste per year in Switzerland, which needs to be landfilled. However, these residues could be potentially used as construction materials after mechanically recovering ferrous and non-ferrous metals. However, the resulting ashes (discharged dry or wet) still contain increased amount of heavy metals (exceeding state regulation) requiring them to be finally deposed on a hazardous waste site. A thermal treatment of these ashes could enable both, to separate and recuperate the remaining heavy metals and an inorganic heavy-metal poor material. The evaporation of metals depends on temperature and can be lowered by addition of chlorides, which would lower the boiling point of most metals by formation of metal chlorides (table 1)."

Jan 1, 2008

By Y. Houbaert, L. Kestens, R. Decocker

"A magneto-elastic model is presented to calculate the orientation dependence of the magnetostrictive strain, observed at saturated magnetisation in ferromagnetic materials with a cubic crystal structure and an arbitrary crystallographic texture. The formula of Becker and Doring is used to express the anisotropy of magnetostriction for a single crystal. In order to simulate the macroscopic average magnetostriction of a polycrystalline aggregate (with an arbitrary texture) the Reuss assumption of the elasticity theory was applied. According to this assumption the various orientations of the polycrystal can defonn without constraints, producing local strain incompatibilities in the microstructure but observing total stress equilibrium. The macroscopic strain is calculated as the weighted average of the individual strains of all orientations composing the polycrystal. The weight factors are determined by the volume fractions of the corresponding orientations of the given texture, which can be measured by standard X-ray diffraction techniques. The model is applied to simulate the variation of magnetostriction (at saturation) with respect to the rolling direction for a standard grade of Goss-oriented electrical steel. A brief comparison with experimental data allows validating the basic model assumptions. IntroductionBecause of tougher environmental constraints, the noise reduction in transformer cores has become increasingly important. It is generally accepted that the main source of noise is magnetostriction, which is known to be caused during the magnetisation process by the movement of 90° magnetic domain walls and the rotation of the magnetisation vector out of the easy directions. Therefore, it is obvious that when a ferromagnetic body is magnetised to saturation, the resulting magnetostriction will be dependent on the distribution of magnetic domains in the initial state.In the literature two coefficients are used to describe the resulting magnetostriction at a saturating magnetic field. The total strain, measured from an arbitrary demagnetised state to technical saturation, is called the saturation magnetostriction, and is denoted by (~)s. The tenn magnetostriction coefficient will be employed to designate the strain measured from the ideal demagnetised state (i.e. one in which no preferred orientation of domains exists) to technical saturation. Failure to recognise the difference between these two quantities has led to considerable confusion in the literature.The magnetostriction coefficient for a single crystal is a well-known property for ferromagnetic cubic materials. In 1939 Becker and Doring [1] have derived the following relation, describing the magnetostriction coefficient for single crystals with a cubic symmetry:"

Jan 1, 2001

By Lucas Lopes da Costa, Sergio Neves Monteiro, Rômulo Leite Loiola

"Composites with DGEBA/TETA epoxy matrix reinforced with thinner and continuous bamboo fibers stripped from culms were mechanically characterized by tensile tests. Specimens with up to 30% in volume fraction of aligned fibers were tensile ruptured at room temperature. The results showed a steady increase in both the ultimate strength and the elastic modulus of the composites with the amount of incorporated bamboo fibers. The fractographic analysis by scanning electron microscopy showed evidence of moderate adhesion between the bamboo fiber and the epoxy matrix. This fiber/matrix adhesion by interaction mechanism apparently justifies the improved tensile properties of the composites.IntroductionIn recent years polymer composites reinforced with natural fibers, mainly those lignocellulosic obtained from plants, have been subject to extensive research works [1-5]. Environmental, economical, societal and technical advantages of these composites are motivating their substitution for similar polymer composites reinforced with synthetic fibers. In particular, R & D efforts have been conducted aiming to replace glass fibers composites that are comparatively more abrasive to equipments, non-recyclable, more expensive, heavier and toxic [6]. Among the many lignocellulosic fiber composites being investigated, those fabricated with bamboo stripped fibers, i.e., fibers longitudinally cut from the culm, still need information to support possible industrial applications. Several works, however, have been dedicated to bamboo stripped fibers as possible reinforcement of polymer composites [7-17]. These works reported mechanical properties that could markedly vary with the type of polymer matrix, the fiber disposition (if continuous, aligned, short-cut, mat interlayered, etc) and the test condition."

Jan 1, 2011

Microstructural investigation has shown that grain splitting or deformation banding ( DB ) develops progressively with increasing strains during cold rolling. Of particular significance to simulating texture development in cold rolled BCC polycrystals is the operation of higher order slip systems other than 110 and, the occurrence of DB in the rolling plane since the latter allows a new relaxation of the shears. Deformation banding ( DB ) model includes grain subdivision in the rolling plane and applies the Relaxed Constraints ( RC ) mechanism for the other shears. An energy criterion for deciding whether deformation banding occurs or not has been postulated, referred to as Deformation Banding Criterion ( DBC ). This paper reports the results of the investigations into the effects of different slip systems, i.e., those based on 110, 112 and 123 slip planes and their combinations using RC, DB and DBC models, in developing simulated BCC rolling textures.

Jan 1, 1999

By Guo-hua Bai, Hong-jing Yuan, Qian Li, Yong-bin Yang, Tao Jiang, Yan Zhang

"The effect of different additives on the bio-oxidation of arsenic-bearing gold ores has been carried out to solve the problems such as long period of leaching, low oxidation rate. The oxidants strengthen the cathodic reaction and thus improve the leaching rate by the increase of electron transfer. Meanwhile, silver catalysis is also effective for the decomposition of arsenicbearing gold ores due to the strengthening of anode reaction. Co-intensification by oxidants and Ag (I) is more efficient to the bio-leaching and the conversion of As (III) because the anode and cathodic reaction of biological oxidation of sulphide ores were both strengthened. The leaching rate reached to 63.94% after bio-leaching 13days by co-intensification of Ag (I) and Fe(III).IntroductionWith the worsening global ecological problems and the gradual exhaustion of available gold resources, metallurgical technology of refractory gold ore has received more and more attention and become possible due to its good advantage of the economic effects and negative effects to the environment. Refractory gold ore, the direct cyanide leaching rate of that is defined as less than 70%, has become an important raw material in gold extraction industry, in which sulfide bearing gold ore represents a large proportion, pyrite and arsenopyrite (FeAsS) is a common gold-bearing mineral. Since the gold is often encapsulated in the crystal lattice of these minerals, destruction or alteration of the ore to liberate the submicron and/or structurally bond gold is necessary[l]. Even if the ultrafine grinding approach also is generally not sufficient for these refractory ores and additional techniques like roasting, pressure oxidation and bacterial oxidation are used to liberate the gold [2]. In the three pretreatment processes, bacterial oxidation is characterized by its new ideas, low cost, no pollution, simple equipment and operation, high leaching index and become the most promising process which has received much attention over time [3-5]. But its further application is limited by some of its own shortcomings, such as long pretreatment time and the toxic effects of arsenic to bacteria on bio-leaching limit."

Jan 1, 2013

By K. Osseo-Asare

Third phase formation, the separation of a solvent extraction organic phase into two liquids, is generally attributed to the limited solubility of the extracted complexes in the hydrocarbon diluents. Much of the research on third phase fomiation, therefore, emphasizes experiments designed to establish the stoichiometry of the species responsible for the limited solubility. This work offers a different approach, based on the recognition that the solvent extraction third phase, in fact, corresponds to the middle phase in a microemulsion fluid system. Using the tri-n-butylphosphate (TBP)-diluent-water-electrolyte system as a model system, current concepts of microemulsion phase behavior are utilized to develop a general framework for interpreting and predicting the patterns of phase behavior in solvent extraction systems.

Jan 1, 1999

By Kejun Liu

Platinum and palladium are usually dissolved together and followed by separation. In this study, the selective leaching of platinum and palladium from a secondary resource, such as dental waste, by using chloride solution (hypochlorite and chlorate) has been developed. Results indicate that about 100% of palladium could be initially extracted by the combination of 0.3 mol/L sodium hypochlorite (NaClO) and 0.068 mol/L sodium chloride (NaCl) at pH 1.2 and 298K in 1.5 hours, or the combination of 0.005 mol/L sodium chlorate (NaClO3) and 6 mol/L hydrochloric acid (HCl) at 298K in 0.5 hour. About 100% of platinum could be extracted from the residue by the combination of 0.47 mol/L sodium chlorate (NaClO3) and 12 mol/L hydrochloric acid (HCl) at 298K in 2 hours.

Jan 1, 2003

By Yuanyuan Wang, Yuhao Ding, Hao Bai, Kang Zhou, Guangwei Du

"In this paper, the list analysis of GHG emissions of aluminum industry was conducted based on the data from typical electrolytic aluminum plants of a China’s northwest province. The results show that under the conditions of average anode effect coefficient as 0.16 times/(cell• day) and anode duration as 5 minutes per day, equivalent emissions of CO2 reached 1.23 ton per ton of aluminum, in which PFC emissions accounted for about 71%. Compared with foreign advanced level, which is 0.87 ton per ton of aluminum under the conditions of average anode effect coefficient as 0.01 times/(cell•day) and anode duration as 0.46 minutes per day, there is much room for China’s aluminum industry to reduce GHG emissions. Since anode effect plays an important role on PFCs generation in electrolytic aluminum process, how to control anode effect strictly becomes the key factor for remarkable reduction of GHG emissions in China’s aluminum industry.IntroductionTechnology of aluminum electrolysis is a mature and efficient process of aluminum production. Due to the huge demand on aluminum worldwide, so resource consumption, energy consumption and pollutant emissions in the process of aluminum production are still large. The global output of aluminum reached 45193 kt in 2012. A large amount of CO2 and PFCs are produced in the process of aluminum production, and the greenhouse effect and environmental pollution caused by emissions of them is a concern. PFCs belong to a powerful greenhouse gas, thus emission reduction of PFCs is very important for aluminum electrolysis industry. At present, China's aluminum production accounts for about 33% of the world's aluminum production, and controlling PFCs emission has become the key point of pollution control of aluminum electrolysis industry in China [1].Taking the case of a typical electrolytic aluminum plant of a China’s northwest province, this paper studies the list analysis of GHG emissions of aluminum industry in China. GHG emissions of a China’s northwest province were calculated through investigating existing situation of aluminum electrolysis industry in the province, knowing capacity, output, main production technology and equipment level of aluminum electrolysis industry, and using the calculation framework and methods of GHG emissions of aluminum electrolysis industry, which were put forward by the intergovernmental panel on climate change (IPCC), the international aluminum association and other organizations at home and abroad. The list analysis of GHG emissions of aluminum electrolysis industry will offer useful information in promoting emission reduction of GHG in aluminum electrolysis industry, improve the efficiency of energy utilization."

Jan 1, 2014

By Gaifeng Xue, Jingxuan Zhou, Shangchao Liu

"Both COD and TOC can characterize organic pollution of coking wastewater. In theory, there is a linear correlation between these two indicators. After continuous monitoring TOC and COD of coking waste water, linear regression relationship between of these to indicators was studied with the use of mathematical statistics. And conversion equation between these two indicators was established, and using t-test method for significance testing. The results showed that the linear relationship of COD and TOC was significant. Also interval estimation of equation slope and intercept were given in the condition of 95% confidence level. A linear regression equation established can be used to indirectly convert TOC to COD with high precision and accuracy.IntroductionBoth chemical oxygen demand (COD) and total organic carbon (TOC) are measure of the degree of characterization for organic pollution of water bodies. The current COD standard analytical methods is Potassium dichromate titration method [1] . there are some disadvantages in this method, such as only part of organic matter in the water bodies being oxidated, the refluxed steps, a long time needed for each measurement, high cost. It is the most important that sulfuric acid silver and mercury sulfate reagents used in the measurement may easily lead to secondary pollution. In contrast, the measurement of TOC is by the method of combustion or Photocatalytic Oxidation. The result could be easily got from the instrument. There are some advantages in this way, such as easy operation, short time and little expenses for each measurement and no secondary pollution 121• In addition, the measurement of TOC has higher degree of precision and accuracy than the measurement of COD both in the determination of calibration standards and actual samples. The meaning and contrast of TOC and COD are listed in the table 1."

Jan 1, 2013

By Juan H. Rojas C.

The Chuquicamata mining and metallurgical complex is the main Division belonging to Corporation Nacional del Cobre de Chile (CODELCO-CHILE) and it accounts for 50% of the 1.4 Mt of fine copper output of the Corporation. It has been producing copper since 1915. The paper refers to the challenges that Chuquicamata has to solve in the near future. These challenges are: the increasing operation costs associated to a 800 m depth pit with low prices in an overstocked copper market; the increasing people's sensitivity to environmental preservation; and, the transformation needed for achieving high levels of organizational effectiveness. According to Corporate policy, Chuquicamata is making efforts to switch from a management style focused on supply to a management style focused on demand side of the industry. In this direction is tempting to establish strategic alliances to develop both new copper products and uses, to rise the metal demand. In more than 80 years of operation, Chuquicamata had exploited just one third of its geological resources. The exploitation of the remaining two third is a huge engineering challenge, taking into account the depth of the deposit, the impurities content, the decreasing ore grades and the transportation distances for waste dumping. All those factors are relevant in the economical process of transforming geological resources into ore reserves. Chuquicamata has other limitations. First, a 20,000 people town just aside the pit that limits the mining rates because of dust generation; second the scarceness of water in the desert area where Chuquicamata deposit is located; and, finally, the new tailing pond is a problem which solution will demand huge engineering efforts and investments. People are the principal factor associated to a company success. In this field, Chuquicamata have been progressing, but much more efforts from people will be necessary to reduce production costs for being successful as any other price-taker within the copper industry. Chuquicamata must develop the skills of its Supervisors to transform them into leaders and entrepreneurs, who additionally have the challenge of passing on their knowledge to non-professional workers. It is an ethic commitment to assure personal and professional growth of workers, as the only sustainable way to get real and integral success.

Jan 1, 1999

By Raj K. Rajamani, James R. Nagel, York R. Smith

In this work, we examine the efficacy of Electrodynamic Eddy Current Separation (EECS) to recover valuable materials from end-of-life solar panels. Traditional rotary-based eddy current separators are capable of excitation frequencies of 1 kHz or less and struggle to economically separate particles smaller than 1 cm. A new design of eddy current separators has been developed at the University of Utah which has no mechanically moving parts. The design is capable of excitation frequencies up to 50 kHz, allowing sorting of particles as small as 1.0 mm. Recently, we have been successful in separating mixtures of Si/Al and CdTe/Al particles (1–3 mm) with recovery and grades greater than 85%, an energy demand of 68 kWh/short ton of sorted material, and throughput of roughly 10 kg/h. Current and future challenges utilizing this method for valuable material recovery from end-of-life solar panels are discussed.

Mar 1, 2017

By Rong Yang, Qijie Zhai, Wenbin Xia, Changjiang Song

"Tills paper focus on the influence of carbon content and cooling rate on the microstructure and phase formation of Fe-Mn-C alloys under near-rapid solidification. When manganese content is about 11wt.%, more s-martensite can be obtained with cooling rate increasing when carbon content is 0.14wt.%, the formed phase changed from a phase to y phase when 0.74wt.% carbon is added to the samples, and when carbon content up to 2.1wt.%, carbide can be obtained in the sample. A host of stacking fault, which attributes to the strain-induced martensite, can be observed in the sample. The microhardness increased with cooling rate increasing, and under the same cooling rate, the microhardness of samples with 0.14wt.% carbon is highest.IntroductionTo obtain high performance materials is eternal pursuit of material science research. Material scientists have explored many new ways to obtain high performance materials from long time ago. Rapid solidification is one of most popular ways to produce advanced materials by obtaining metastable phases, because it is widely known that the solidification of metals in metastable phases gives access to a whole range of materials with novel properties [1]. Furthermore, nowadays metastable materials have been extensively used in many fields, for example, many of our modem high performance materials such as steel products or aluminum alloys for aeronautical applications are in the form of metastable rather than stable phases [1]."

Jan 1, 2012

By C. A. Morais

The present work describes the development of an efficient and relatively simple process to obtain high grade CeO2 from a mixed rare earth chloride solution. The process involves cerium oxidation and precipitation by addition of a KMnO4-NaCO3 solution. The experiments were carried out at room temperature (25 1° C). The results indicated that the major parameters affecting cerium recovery are the molar ratio of KMnO4/Ce, the initial acidity of the chloride feed solution and final pH of Ce(OH)4 precipitation. In strong acid solutions (pH < 1), the oxidation of Cl to Clo took place in addition to the oxidation of Ce(III) to Ce(IV), so increasing the permanganate consumption. Conversely, low acidity (pH >3) led to coprecipitation of the other rare earth elements. Under the selected conditions, cerium was selectively precipitated as ceric hydroxide, together with some manganese dioxide. Further purification was carried out by the dissolution of Ce(OH)4 in HCl, followed by precipitation as cerium carbonate. The filtrate was neutralised with a Na2CO3 solution in order to recover the associated rare earth elements for further separation. The final product, assaying 99.7 % CeO2, was obtained with a recovery of nearly 100%.

Jan 1, 2003

By Peng Fan

Nitride capacity is usually employed as the measure of slag?s ability to remove nitrogen from liquid metal, since nitrogen distribution ratio between slag and metal can be calculated from nitride capacity provided that the value of oxygen activity in liquid metal is available. However, during liquid metal refining processes, oxygen activity in liquid metal is usually unknown and thus it is impossible to get nitrogen distribution ratio from nitride capacity under this usual condition. In this paper, thermodynamic analysis indicates that the activity coefficient of nitride in slag can be used to measure slag?s ability to remove nitrogen from liquid metal, because nitrogen distribution ratio between slag and metal can be calculated from the activity coefficient of nitride in slag provided that the content of oxygen potential controlling element like Al in liquid metal is available. Review of reported nitrogen removal studies and our recent study has verified that for a given Al content in metal, the lower the AlN activity coefficient in slag is, the higher the nitrogen distribution ratio. Titanium monoxide based slag has been found to be much more effective to remove nitrogen than other slags. Since Al content in liquid metal is usually available during liquid metal refining processes, AlN seems to be a better measure of slag?s ability to remove nitrogen from liquid metal.

Jan 1, 2006

By James A. Sommers

Hydrolysis of NbC15 is used to recover oxide values for ceramic and metals production. Reaction of NbC15 with water is rapid, exothermic and vigorous, yielding a gelatinous slurry. In contrast, dissolution of NbC15 in 12 N HCl is endothermic, resulting in a clear yellow solution. Such solutions can be de-hydrochlorinated by controlled contact with air, to precipitate a tantalum¬rich solids, depleting the liquid of its tantalum content. In this way, cheap, useful Nb-Ta partial separation is achieved. The separation is based upon differential oxide-chloride stability. Nb2O5 with <200 ppm Ta/Nb has obtained from starting levels of 2000 ppm. Observations are made on the different types of hydrolysis.

Jan 1, 1992

By Norihiro Murayarna

Hydrothermal synthesis of K type zeolite was carried out by using coal fly ash as a raw material and KOH as an alkali source. The change in various physical properties of the obtained zeolite, such as the kind of zeolite crystal, cation exchange capacity, surface structure of zeolite and particle size distribution were investigated through the overall reaction of zeolitization. The reaction mechanism of K type zeolite from coal fly ash was investigated from these results in this study

Jan 1, 2002

By T. Scarazzato, J. M. S. Jesus, D. C. R. Espinosa, J. A. S. Tenório

The development of separation process for the wastewater treatment in distinct industrial process have been applied for recover water and inputs. Electrodialysis is an example of separation process that have been studied for electroplating wastewater treatment. The use of ion-exchange membranes and an electric energy allows the selectivity separation of ions in a solution. The 1-hydroxyethane-1,1diphosphonic acid HEDP is an organic acid that is has been applied for the cyanide substitution in electroplating baths, and in this condition the electrodialysis has showed recover potential. The ion-exchange membrane used in an electrodialysis process contain organic sample are exposed for extreme conditions. These conditions can provide degradation structure and loss of permselectivity, which causes unusual membrane properties. The aim of this study is evaluate the influence of CuHEDP complexes in synthetic ion-exchange membranes using electrochemical test.

Mar 1, 2017

By Petr Sulovsky, Pavel Leber, Jaroslava Ledererova, Miroslav Svoboda

"The properties of raw materials used for the production of building materials play an essential role in their choice. Industrial waste materials can in some cases improve the performance of new building materials, when compared with classical raw materials. The addition of waste can however negatively impact some of the building material´s characteristics, influencing its stability, service time, durability, and can introduce undesirable variation of certain characteristics over time. It is necessary that each secondary raw material intended for such use be thoroughly investigated in terms of its chemical, physical, and mechanical properties, with special attention paid to the risk components and risk parameters. It is necessary to make many- sided technological tests in relation to the required characteristics of the resulting materials for each chosen application. Moreover, the limit values for the critical (risk) parameters, which the given secondary raw material must satisfy to be used in a specific technology, need to be defined. Introduction The risk components in the industrial waste materials to be used in the production of building materials fall into two groups: - components that pose a risk of development (instant or delayed) of a process deleterious to the utility properties and durability of the resulting materials. Such processes include volume change (expansion as well as shrinkage), alkali-silica reaction, delayed ettringite formation, thaumassite attack, aggressive carbonation, etc. - elements or components that can, if released from the waste-containing building material, pollute the environment. They involve the so called potentially hazardous elements as well as compounds like fenols, PCB, PAHs etc. From the viewpoint of the presence of both groups of risk components, the wastes can be classified as: • environmentally inert waste materials. They are produced in the largest volumes and do not pose a threat to human health. Their physical and/or chemical characteristics fail to satisfy all requirements for utilization in ordinary production. The aim of technology design is to work them into the building products with suitable utility properties. • easier workable waste materials containing toxic components are produced in large volumes. In spite of the content of toxic components, their physical and chemical properties make them suitable for ordinary production, provided that the harmful substances are immobilized by the chosen technology."

Jan 1, 2008