Valorization of Iron Ore Beneficiation Rejects from the Iron Deposit of Boukhadra (Algeria) in the Fabrication of Ordinary Portland Cement

Abstract

The Boukhadra’s iron deposit supplies the El–Hadjar, the largest ironwork in the country located in the northeast of Algeria. The quality of the iron ore affects negatively the ironwork production, therefore a beneficiation of the iron ore by magnetic separation is considered as an appropriate solution. However, this technique is known for the generation of important quantities of nonmagnetic parts considered as rejects. The treatment or stock of these rejects is likely to have an important cost and creates environmental problems. In this study, the beneficiation process by magnetic separation of the Boukhadra’s iron ore and the valorization of the rejects from this beneficiation process as raw materials for Portland cement production are presented. Three rejects from the different beneficiation processes were mixed separately with marl and limestone from the same deposit of Boukhadra for the elaboration of three Portland cements.The mineralogical compositions of the raw materials and the produced clinkers in addition to the hydration products of the harden paste were studied by X-rays diffraction. The chemical composition of the clinker and raw materials was determined using X-rays fluorescence. The burnability of the clinkers has been characterized on the basis of the free lime content and the degree of crystallization of the clinker phases. The proportion of the different phases has been determined using Bogue calculation and Rietveld method. The compressive strength and setting time were determined according to French standards. The obtained clinkers are composed from Alite, Belite, Ferrite and Aluminate. The proportions of these phases are in abdication with the composition of regular Portland cements. These phases showed a good crystallization at 1400 °C. The obtained cements have mechanical and chemical proprieties that meet the requirements for Portland cement Class 42.5 according to NF P 15-301 which is an ordinary Portland cement. The results of this study conclude that the rejects used during this work are compatible with a valorization as raw materials for the fabrication of Portland cement.