ION TEOREANU, PAULA CARLAN, ION CHICINAS
|Al2O3-Ni Cermets. Technological properties of components and related precursor mixtures|
MARIA SPATARU, MARCELA MUNTEAN, OVIDIU DUMITRESCU
|The influence of grinding time upon ceramic shaping|
CONSTANTIN AUREL DIMITRESCU
|Relations between the fineness parameters of portland cements|
MARIA GHEORGHE, ECATERINA ANDREESCU, DORIN VOINITCHI
|Aspects regarding the durability of the concretes based on high blast furnace slag content cement|
|Waste co-incineration in the clinker kilns at Carpatcement Holding - impact on emissions and on clinker quality|
|DANIELA PARASCHIVESCU, FLORENTINA MIHAILESCU, ELENA DIMA, CRISTIANA RADULESCU, ANCA DRAGOMIR, SORIN JINGA||Integrated pollution control system in the container glass manufacture|
|ZENO GHIZDAVET||Modern methods for process prediction and optimization. Applications|
Al2O3-Ni Cermets. Technological properties of components and related precursor mixtures
Present paper deals with the examination of pressability and sinterability of g-Al2O3 (ceramic component) and Ni (metallic component) powders for Al2O3-Ni cermets fabrication. Similar characteristics of precursor mixtures for cermets are also studied, with or without admixtures. There is considered the influence of cermets composition and processing route of Ni powder upon those technological parameters. The obtaining routes used allow one to manufacture cermets with good results where using traditional technology.
The influence of grinding time upon ceramic shaping
Calcined alumina and zircon are used in ceramic and refractory industry thanks to their mechanical, electrical and thermical properties. Agueous suspensions from these materials were prepared for shaping through pouring in plaster molds. The forming of ceramic body depends on the suspensions and plaster moulds properties. The wet homogenizing-grinding time of the raw materials and the additions mixture determines the mean grain size and their grain size distributions. These have a great influence upon properties both of ceramic suspensions and of shaped products through pouring from them. The paper presents used grinding times and some suspensions properties such as: mean grain size and grain size distributions, volume weight, pH, viscosity. The influence of mixing time (homogenization time of the plaster with the water) upon the water absorption by plaster moulds is produced through mean diffusion coefficient, the formed ceramic body mass and the absorption time of a drop of potassium permanganate solution on the formed body. Some aspects of the behaviour to pouring as : ceramic body thickness, green density are also shown.
Relations between the fineness parameters of portland cement
Relations between the main particle size parameters (the position parameter and the slope of the RRSB distribution, the particle sizes x80 and x50, the residue R0032, and the 3–32 μm fraction) and the Blaine specific surface area of cement CEM I and CEM II/A–S with up to 15% blast furnace slag have been established on the basis of experimental data. These relations may be useful both in optimising the particle size distribution of cement in terms of physical and mechanical characteristics and in process calculations concerning the specific energy consumption in grinding cement with such particle size distribution.
Aspects regarding the durability of the concretes based on high blast furnace slag content cement
The paper presents experimental data referring to concrete durability having high strengths class (of C55/67, C60/75 and C75/85) and high durability - impermeability grade of P1210, P1610, resistance to chemical aggressively media class XA3 and freezing –thawing resistance of G150, as according of EN 206-1:2002
The concretes were obtained using high blast furnace slag content cement type CEM III/A 52.5R according to EN 197:2002, aggregates - sand and crushed stone (as according EN 12620), super plasticizer and air entraining admixtures.
The concrete resistance to chemical attack (short term of 210 days) was evaluated by measuring of the properties evolution referring to the volume variation, water absorption, ultrasonic impulse velocity and flexural strength, by testing of the samples cured in two different media - into potable water (reference) and into aggressive media as according to XA3 class. Also, were carried out measuring of the carbonation depth and chloride penetration of the concretes.
Wastes co-incineration in the clinker kilns at Carpatcement Holding - impact on emissions and on clinker quality
CARPATCEMENT Holding SA belongs to the German group HeidelbergCement, and operates three cement plants: Fieni (Dambovita county), Deva (Hunedoara county) and Bicaz (Neamt county).
Co-processing of wastes resulted from other industries for substitution of raw materials and fuels is a service that cement industry can provide for the society, contributing not only to diminish the resources consumption, but also to reduction of the impact of the cement plants.
Based on the technical capabilities of the clinker kilns in Carpatcement Holding, the paper proves that use of alternative fuels based on wastes in the cement kilns does not increase the stack emissions, but on the contrary in some cases contributes to emission decrease and also does not influence the ciment qualities.
The statements from bibliographic sources found in this paper are confirmed by the modeling and monitoring presented by the same author in the paper “Results of mathematic modeling and emission monitoring of waste co-incineration in clinker kilns at Carpatcement Holding”.
Integrated pollution control system in the container glass manufacture
The National Glass Institute carries out within the MENER Program framework a project concerning a system for the Integrated Pollution Prevention and Control in the manufacturing of container glass which has as objectives: identification of emission sources, soil quality assessment and measures of emissions reduction in order to help the Romanian glass manufacturers to comply with the European environment and the sustainable development requirements
The experimentation of the model has benefited from the support of the industrial partner in the project SC STIMET SA.
Maintenance/repair measures, emission monitoring and wastes management were set for the industrial partner on the base of the model of the IPPC system.
Modern methods for process prediction and optimization. Applications
Alternative mathematical methods to deterministic modeling could be – for the time being – the only possible approach to describe difficult-to-be-modeled systems. As the theoretical part of the methods used here is well represented in literature, in that work efforts were oriented towards a practical, realistic purpose. Application will consider the running of a cement grinding plant.
Romanian Journal of Materials