CONTENTS OF VOL. XXII/2014
Metallurgy and New Materials Researches, No. 4/2014
Refractory material with high strength to direct contact with molten metal
Aspects regarding to patinated steel gouging
Aspects regarding the achievement of vertical welding joints
Chemically bonded magnesia – phosphates high temperature resistant ceramics
Removal of Ni(II) from aqueous solution using a novel impregnated sorbent
Abstract 1
The paper presents research results in the laboratory phase carried out by a team of researchers from the company Cermax 2000 Patents SRL Bucharest, in the refractory materials with high strength to direct contact with molten metal.
Authors focused their effort on the refractory materials with outstanding thermal and mechanical features, performed by pressing, for replacement of usual materials that make up the wear layer of steel ladles.
The results obtained, so far in the laboratory stage, are promising, made material characteristics corresponding proposed technological purpose. The thermal conductivity has values between 0.53 – 0.59 W/m·ºC, the compressive strength is between 22 – 25 MPa, the refractoriness is 1560 – 1600 IP and the material density is between 1.25 – 1.35 g/cm3.
Keywords: refractory material, ladle, metalurgy, high strength, thermal conductivity
Abstract 2
Gouging is a process for thermal processing or treating of metal parts by which the molten metal that belongs to the part/piece is removed by a strong air jet.
The melting of the metal is due to the temperature released by the electric arc between a graphite electrode and workpiece surface.
Gouging can be made with a special or particular gouging electrode OK 21.03, a graphite electrode (arc-air gouging) and plasma.
In the present paper are presented aspects concerning the application of these gouging methods.
Keywords: arc-air, gouging, gouging technology
Abstract 3
The vertical MAG welding procedure is a difficult position to be executed because the trend of the molten bath flowing.
This article aims to present the achievement of vertical welding joints with a linear device with a radial oscillation system that should achieve automatic vertical welds. Through the correlation of the welding parameters with the torch movements the best values were determined in order to achieve welds with a good appearance.
Key words: vertical welding, welding device, welding parameters
Abstract 4
Present paper describes the investigations on chemically bonded magnesium masses and assesses their potential as binder for refractory materials fabrication.
The MgO – P2O5 – H2O type binder systems have been studied and compared. As liquid component,there were used various ammonium phosphates and sodium phosphates salts solutions carried out the trials with magnesia phosphate cements.
Details are given as concern the hardening properties of magnesia-phosphates cements for compression strengths of specimens after setting at room temperature during 1 day, 3, 7, and 28 days; setting period at room temperature; compression strength evolution after firing in the 20 – 1750oC temperatures range; open porosity, bulk density, linear shrinkage after firing at 1750oC . Reaction bonds for a MgO-(NH4)2HPO4 -H2O cement, were investigated at hardening at cold and after firing.
The results emphasize the potential of chemical bonding to obtain strong and dense refractories.
Key words: binder systems, magnesia phosphate cement, chemical bonding
Abstract 5
Contaminated soils present a major global health problem especially in urban areas with dense population.
In accordance with Soil Framework Directive (COM(2006)232) the UE member states will must prevent further contamination and establish an inventory of contaminated sites in their country.
For this scope it is necessary to collect a lot of samples in the field and carried out the laboratory analysis. An alternative method for rapid determination of the contamination grade of soils is the use of field – portable X-ray fluorescence (XRF) instrument.
The goals of this paper are: to establish how the analysis time and particle size of soil influenced the magnitude of the results and to determine the data quality obtained with portable XRF instrument. The data obtained with XRF measurements were compared with laboratory results.
Key words: (D.a) heavy metals, (D.d) pollutant, (B) X-ray method, XRF, polluted soil
Abstract 6
Population expansion and growing industrialization have been contributed to the release of increased heavy metal content in the environment. It is well known the problems related to the ubiquitous nature of heavy metals, their toxicity even in traces, their tendency for bioaccumulation in food chain, their non – biodegradability and their ability to undergo transformations. In this context, removal, separation and enrichment of heavy metals play an important role for environmental remediation as well as for the analysis of wastewaters. The most commonly used methods for the removal of heavy metal ions from industrial effluents include: chemical precipitation, solvent extraction, oxidation, reduction, dialysis/electrodialysis, electrolytic extraction, reverse osmosis, ion exchange, evaporation, cementation, dilution, adsorption, filtration, flotation, air stripping, steam stripping, flocculation, sedimentation. Amongst all treatments proposed, the removal of metal ions by their adsorption on chelating sorbents is in many cases the method of choice, due to its selectivity, highly separation efficiency, good reproductibility of retention parameters and simplicity of operation. Impregnated sorbents are chelating resins whose functional groups are not chemically bounded to the matrix, but fixed on the surface with physical weak forces.
This study reports a novel impregnated sorbent prepared by the immobilization of 5.7-dibromo-8-hydroxyquinoline on the polystyrene non – polar support Purasorb. The batch adsorption capability of this impregnated sorbent for the removal of Ni(II) ions from diluted aqueous solutions was investigated as a function of initial pH, contact time, temperature and concentrations of loading reagent, methanol and metal ion. The obtained results suggest that the proposed sorbent is a promising material for the development of a sorption technology for the removal of Ni(II) ions from aqueous streams.
Key words: nickel, sorption, 5.7-dibromo-8-hydroxyquinoline, Purasorb