Journal of Metallurgical Engineering
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Open Access journal
ISSN (Print) 2168-555X - ISSN (Online) 2168-5568
Published by Science and Engineering Publishing Company [49 journals]
- Centrifugal Concentration of Rare Earth Minerals from Calcitic Gangue
Abstract: Centrifugal Concentration of Rare Earth Minerals from Calcitic Gangue
Author Doug SchrinerCorby Anderso
Flotation separation of bastnaesite from carbonate gangue has proved to be an exceedingly difficult task, yet it remains the dominant unit operation for beneficiation of rare earth element-bearing minerals. The high specific gravity of these minerals (bastnaesite and monazite) in relation to the gangue (calcite) suggests the opportunity for beneficiation through gravity separation. The purpose of this investigation is to determine the applicability of centrifugal concentrators to the beneficiation of a bastnaesite ore from southern California containing large amounts of calcite gangue. Mineral Liberation Analysis (MLA), heavy liquid separation, and a Falcon Concentrator were used to show the amenability of this ore to gravity separation. From a feed averaging 12% calcium, 6.7% barium, and 3.4% total rare earth elements (TREE: lanthanum, cerium, praseodymium, samarium, and neodymium), an optimum product of 14.5% calcium, 13.13% barium, and 7.8% rare earth elements was successfully generated with the Falcon using a feed with the finest particle size distribution, lowest feed rate, and lowest G-force.
- A Case Study: Corrosion Failure of Tube Heat Exchanger
Abstract: A Case Study: Corrosion Failure of Tube Heat Exchanger
Author Ibrahim M. GhayadZeinab Abdel HamidNasser Goma
A failed heat exchanger was sent to CMRDI to investigate the possible causes of leaks occurred in the tubes of the heat exchanger. The heat exchanger tubes were made of stainless steel 316 straight type. The heat exchanger served to heat up water basin (desalinated water) during the cold winter time. The water contains a high chloride level. Corrosion testing indicated susceptibility towards pitting corrosion especially at high temperature. It was suggested that controlling chloride level and proper adjustment of pH are the optimum solutions to avoid corrosion of heat exchanger pipes.
- Laser Surface Treatment of Metal Implants: A Review Article
Abstract: Laser Surface Treatment of Metal Implants: A Review Article
Author Ibrahim M. GhayadNabil NassifWafaa Ghane
Metal implants are mainly fabricated from stainless steels, cobalt base or titanium base alloys. In addition to mechanical properties, metal implants must have excellent corrosion resistance as well as good bioconductivity and biocompatibity. Biocompatibity is achieved on a metal implant by the application of proper surface treatment. This paper reviews the techniques used for surface treatment of metal implants with a special focusing on laser surface treatment as a new and promising technology for surface treatments. Published papers indicated that surface treatments performed on metal implants are mainly of two types; the first concerned with the deposition of hydroxyapatite (HA), bone-like material while the second focused on the deposition of diamond-like carbon (DLC). Present review covers in detail the laser systems used for either HA or DLC coating.
- Corrosion Failure of 4" Pipeline of a Gas Production Well in Egypt Western
Abstract: Corrosion Failure of 4" Pipeline of a Gas Production Well in Egypt Western Desert
Author Zeinab Abdel HamidIbrahim M. GhayadNaser Goma
A corroded part of a 4" pipe of AG which is a gas producing well came to production since July 2011. It was sent to CMRDI to investigate the failure analysis of the failed pipe. Severe corrosion was observed in the 6 O’clock position inside the pipe. Combined erosion and pitting corrosion occurred on the bottom (6 O' clock) of the failed pipe. The Corrosion attack is thought to occur due to associated condensate waterwhich is relatively high (as this case).Water is mostly acidic due to the high concentration of CO2 which dissolves in water forming carbonic acid H2CO3. High corrosive nature of water is also evident from the great amounts of chloride present in the condensate water. It is suggested that proper treatment of the problem can rely on the use of suitable corrosion inhibitor and also increase the efficiency of dewatering process to decrease the amount of water associated with the flowing gas.
- Comparative Reduction Behavior of Cement Coated Iron Ore Pellets
Abstract: Comparative Reduction Behavior of Cement Coated Iron Ore Pellets
Author M. BahgatS. AhsanS. LakdawalaH. Hanaf
In the moving-bed shaft direct reduction processes, such as Midrex and HYL III, the avoidance of sticking is absolutely essential. In order to prevent sticking of pellets a coating material, basically inactive under the reducing conditions prevailing in the shaft furnace, should be applied to cover the outer layer of the pellets. In the present work cement coating is applied for iron ore pellets in various concentrations. 12, 16 and 20% cement slurry concentrations were used to have a coated cement amount of 0.5, 0.75 and 1.0 Kg/ Ton iron ore. Using thermogravimeteric technique the coated samples were reduced with hydrogen/carbon monoxide mixture which is somewhat simulating the composition of the reducing gas in Midrex furnace. The iron ore pellets and reduced samples were characterized by XRD, XRF and SEM. The influences of various coating conditions on the reduction behavior and the morphology were investigated. As reduction proceeds, the rate of reduction was highest at the early stages and decreased as reduction proceeds till the end of reduction. Comparatively the reduction rate of the coated iron ore pellets are clearly effected by the different coating conditions.
- Potential of Recycled Aluminium Cans and 215 µm Sized Eggshell Powder
for Low Cost Metal Matrix Composites
Abstract: Potential of Recycled Aluminium Cans and 215 µm Sized Eggshell Powder for Low Cost Metal Matrix Composites
Author J. O. AgunsoyeS. A. BelloA. A. YekinniI. A. RaheemM. M. IdehenreT. E. IdegbekwuA. D. Oderind
The potentials of recycled aluminium cans with 215 µm sized eggshell powders to produce a useful engineering composite material were investigated. the stir cast method was used to enhance proper mixing of the composite melt prior to pouring exercise. the process involves gradual increase of the eggshell powder additions to the aluminium can melt from 2 to 12%. the composite melt was poured into a preheated steel die mould to produce 250 x 120 x 120 mm rectangular bars. the bars were machined to standard samples for mechanical and physical property investigations. morphology of eggshell powders wasexamined with the aids of scanning electron microscope. the results showed a considerable increase in tensile strength, young’s modulus of elasticity and hardness values. the increase is attributable to formation of dislocation loop and pile-up due to impingement/hindrance to dislocation movement by eggshell powders within the aluminium can matrix. however, there was a noticeable decrease in tensile strain and impact energy respectively. furthermore, the developed composites are lighter (lower density) than the control sample without eggshell powder additions.
- Bimodal and monomodal diamond particle effect on the thermal properties of
diamond-particle-dispersed silver matrix composite fabricated by SPS
Abstract: Bimodal and monomodal diamond particle effect on the thermal properties of diamond-particle-dispersed silver matrix composite fabricated by SPS
Author Kiyoshi MizuuchiKanryu InoueYasuyuki AgariMasami SugiokaMotohiro TanakaTakashi TakeuchiJun-ichi TaniMasakazu KawaharaYukio MakinoMikio It
Diamond-particle-dispersed silver (Ag) matrix composites consisting of monomodal and bimodal diamond particles were fabricated in spark plasma sintering (SPS) process, where the mixture of diamond, pure Ag and pure Si powders were consolidated in liquid and solid co-existent state. Microstructures and thermal properties of the composites fabricated in such a way were investigated and the bimodal and monomodal diamond particle effect was evaluated on the thermal properties of the composites. The composites can be well consolidated in a temperature range between 1113 K and 1188 K and scanning electron microscopy detects no reaction product at the interface between the diamond particle and the Ag matrix. Relative packing density of the composite containing monomodal diamond particles decreased from 97.4% to 93.4% with increasing volume fraction of diamond between 50% and 60%, whereas that of the composite containing bimodal diamond particles was as high as 99~97% in a volume fraction of diamond up to 65%. The composite containing bimodal diamond particles revealed the thermal conductivity around 720 W/mk at 60 and 65% of the volume fraction of the diamond particles and it was higher than that of the composite containing monomodal diamond particles in a volume fraction of diamond higher than 55%. The coefficients of thermal expansion (CTEs) of the diamond-particle-dispersed Ag-matrix composites fall in the upper line of Kerner model, indicating good bonding between the diamond particle and the Ag matrix in the composite. The CTEs of Ag-matrix composites containing bimodal diamond particles are 6.76×10-6/K at 62 vol.% diamond and 6.54×10-6/K at 65 vol.% diamond.
- Numerical Calculation of the Comprehensive Heat Transfer Coefficient on
the Surface of Rail in the Spray Cooling Process
Abstract: Numerical Calculation of the Comprehensive Heat Transfer Coefficient on the Surface of Rail in the Spray Cooling Process
Author Ge LiZhimin LiuLin chenXianqin Ho
In order to determine comprehensive heat transfer coefficient on the surface of rail in the spray cooling process, the secondary development of the front and back processing module by the Python scripting language for ABAQUS. The Python scripts are written, and cooling curve of rail spray cooling experiment was used to calculate the comprehensive heat transfer coefficient. The results show that Python script can realize the function of automatically creating rail spray cooling model and iterative calculation for the comprehensive heat transfer coefficient under ABAQUS environment. And the time-varying temperature curve of rail which was calculated by using the comprehensive heat transfer coefficient approximates the experimental value.
- Effect of Manganese Sulphide Shapes on the Work-hardening Coefficient of
Hot Rolled Structural Steel
Abstract: Effect of Manganese Sulphide Shapes on the Work-hardening Coefficient of Hot Rolled Structural Steel
Author Ahmed I. Z. FarahatZainab Abdel-hamidNasser Goma
This paper studied the effect of non-metallic inclusions shapes (manganese sulphides on the tensile testing behavior, the work-hardening coefficient and rate. Longitudinal and Transverse tensile testing was carried out. The fracture surface was studied after tensile testing. Chemical analysis for the non-metallic solution was conducted using EDS-SEM. Tensile testing was carried out in thickness direction and in parallel to the direction of rolling. The work-hardening coefficient (with tensile samples of the thickness) increases with the types II and III. It is found that the work-hardening rate for types of non-metallic inclusions is similar and has critical change. It is also observed that the non-metallic inclusions Type II and III can resist the crack propagation due to crack tip or plastic zone at the onset of crack.