This article describes a methodical framework that combines two specific methods of Lean management, namely the ABC method and the MRP planning method. The article further argues that combining the ABC inventory method with subsequent MRP planning is beneficial if the combination is implemented in practice. To demonstrate the benefits, the framework is tested using a case study company. The presented case-study problem is to reduce the number of changeover downtimes in the environment of an engineering production company. The researched company deals with the problem of setting up production lines in a way to minimize the number of downtimes within one work shift. Within the solution, four possible variants of the production plan are presented. By combining the ABC and MRP methods, up to four changeovers can be saved, which in financial terms represents a saving of about EUR 450,000 per year.
This paper describes the synthesis of tungsten disulfide (WS2) powder by the sulfurization of tungsten trioxide (WO3) particles in the presence of additive potassium carbonate (K2CO3) in nitrogen (N2) atmosphere, first at lower temperature (200 °C) and followed by reduction at higher temperature (900 °C). In addition, the ultrasonic spray pyrolysis of ammonium meta-tungstate hydrate (AMT) was used for the production of WO3 particles at 650 °C in air. The HSC Chemistry® software package 9.0 was used for the analysis of chemistry and thermodynamic parameters of the processes for WS2 powder synthesis. The crystalline structure and phase composition of all synthesized powders were analyzed by X-ray diffraction (XRD) measurements. The morphology and chemical composition of these samples were examined by scanning electron microscopy (SEM) combined with energy dispersive X-ray analysis (EDX).
This paper presents experimental results obtained by agitation leaching of hazardous waste sample -flux skimming. Such flux is formed by Zn(OH)Cl and NH 4 Cl phases. Distilled water and water solutions of hydrochloric acid were selected as a leaching media. The aim of this study was to determine optimal conditions of zinc extraction into the solution. The apparent order of reaction with regard to the initial HCl concentration in the leaching solution is n=0.18 in the concentration range from 0.01 mol.dm -3 to 0.25 mol.dm -3 . The obtained results also indicate that the temperature does not significantly affect zinc extraction. The value of apparent activation energy was estimated to E a =3.985 kJ.mol -1 . Optimal liquid to solid ratio L:S=80 for both used leaching media was also determined experimentally as well as the stirring rate at 200 rpm.
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