Xu Zhenming

Improvements of the Recovery Line of Waste Toner Cartridges on Environmental and Safety Performances

A physical recovery line had been constructed in plant for the increasing waste toner cartridges in previous work. However, with the production, severe lacks of the line emerged: (1) there was little proper technology of treating the collected toner; (2) strong noise was produced from the line and influenced the health of worker. For disposing toner properly, a new collected system of toner was developed. An air current separator (ACS) was designed to separate organic materials from inorganic materials of toner. Then, the separated organic materials can be incinerated and the inorganic materials can be dumped. Movement behaviors of toner particles in the ACS were analyzed, and the optimized operation parameter (13.5 m/s) of air current speed was obtained by theory analysis and experiments. For controlling the noise, noise levels emitted from the different process of the line were measured. The results indicated noise levels emitted from crusher (95.2 dB(A)) and agitator/magnetic separator (AMS, 91.9 dB(A)) were greater than the permissible noise exposure level of the Occupational Safety and Health Standards (90 dB(A)). The noise levels of other processes of the line were relatively safe. An acoustic hood was developed to reduce the noise levels of the crusher and the AMS. Then, the noise levels were both decreased to 67.6 dB(A). This paper provided important data for the environment on the industrialization of waste toner cartridges recovery.

Elimination of Fe in Al-Si cast alloy scrap by electromagnetic filtration

Fe in Al-Si cast alloy scrap melt was eliminated by electromagnetic filtration of primary iron-rich phases, which were formed by adding Mn in the melt. The principle of electromagnetic filtration is that the electromagnetic force scarcely acts on the primary iron-rich phases due to its low electric conductivity as compared to the melt. As a result, a repulsive force exerts on the primary iron-rich phases to move them in the direction opposite to that of the electromagnetic force. It has been found that the forming temperature of primary iron-rich phase increases gradually with the increment of ratio of Mn to Fe (Mn/Fe), and that the iron-rich phases are formed as primary phases, they appear as massive particles with size of 30–80 μm. Experimental results show that the primary iron-rich phases are separated from Al-Si alloy scrap melt and are collected in the electromagnetic separation chamber. Fe content in the cast ingot decreases from 1.20% to 0.41% by electromagnetic filtration, which can meet the demand for casting. This new technique is highly efficient and available for continuous processing compared with natural settling and filtration methods. It offers a possibility for recycling high quality aluminum alloys.

An in situ surface composite produced by electromagnetic force

Because of the different conductivities between the primary phase (low electric conductivity) and the metal melt, electromagnetic force (EMF) scarcely acts on the primary phase. Thus, the primary phase is moved in the direction opposite to that of the EMF when the metal melt with primary phase solidifies under an electromagnetic field. Based on this, a new method for production of in situ surface composites by EMF is proposed. This method has the advantages of being simple and inexpensive, and therefore, has bright prospects for application.

Eutectic growth in as-cast medium manganese steel

Abstract Eutectic growth in as-cast medium manganese steel modified by a Mg–Ce–Ti–Si compound was investigated by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Results show that the eutectic ((Fe, Mn) 3 C and austenite) is formed between austenite dendrites at the end of solidification due to the segregation of C and Mn which is enhanced by modifying elements. MgS and CeO 2 are formed preferentially during solidification to act as heterogeneous nuclei for the crystallization of the eutectic. The Mg, Ce and Si adsorb and enrich on the growing surface of the eutectic during crystallization, which makes the crystallization model of the eutectic turn from facet–non-facet to non-facet–non-facet. The mechanism of the nodularization of the eutectic can be explained by (1) the heterogeneous nuclei, (2) the influence of the modifying elements on the crystallization of the eutectic and (3) the eutectic growth limited by the small melting pool between austenitic dendrite arms and austenitic grains.

Microstructure and properties of austenite-bainite steel matrix wear resistant composite reinforced by granular eutectics

A new austenite-bainite steel matrix wear resistant composite reinforced by granular eutectics (abbreviated ABGE composite) has been obtained by controlling the solidification structure of the steel melt, which only contains manganese and silicon, with modification of Al-Mg-Ce compound and air-hardening. It has been found that the granular eutectic is a pseudo-eutectic of austenite and (Fe,Mn)3C, which is formed between austenite dendrites during solidification due to the segregation of C and Mn enhanced by modifying elements. The granulation of the eutectic can be explained by the heterogeneous nuclei of MgS and CeO2 and by the influence of the modifying elements on the crystallization of the eutectic. The eutectic and bainite contents are 4%–10% and 20%–40%, respectively. The size of the eutectic is 5 μm–20 μm and its microhardness is HV800-1200. The wear resistance of the ABGE composite is much higher than that of the austenite-bainite steel, austenite-bainite ductile cast iron and medium manganese steel with nodular carbides under low and medium impact working condition because the granular eutectics effectively lighten the intrusion of abrasives into the worn surface and microcutting by abrasives on the worn surface and austenite-bainite matrix structure has high strain-hardening ability.

Effects of hydrogen in lanthanum on hydrogen content in Al-alloy

Abstract The effects of lanthanum on hydrogen content in Al–Si alloy are investigated by Degle method and other methods. The results indicate that the hydrogen content in liquid aluminum alloy has been considerably increased after adding than 0.3% lanthanum, the defects of the needle holes in solidification samples under negative and standard pressure also increase. The relationships between hydrogen content in liquid aluminum alloy and the time after adding lanthanum present two different processes: the increase and decrease of the calculated hydrogen in Al-alloy melt. The hydrogen in lanthanum is the main reason for the results. The X-diffraction spectrum of lanthanum indicates that the starting lanthanum contains small quantity hydrides. The relationships between the addition of lanthanum and the resulting hydrogen concentration in liquid Al-alloy are also discussed.