Flotation tests have been used in order to achieve the purposes of this study which are: To obtain the highest recovery with a maximum grade of P 2 O 5 from the tailing generated by the phosphate plant of Djebel Onk in the East of Algeria. To get a good concentrate from the rejections, which gives an added value to the national economy. To preserve the human life and finally to protect the environment from the heavy metals contained in the tailings. Methods. To reach our goals we have used: the granular and XRD analysis to characterize the tailing composition so as to choose the right reagents and conduct a good flotation. Flotation tests were carried out using Sodium Oleate as a collector and alkyl hydroxamic acid (AERO 6493) as collector and frother, zeta-meter system to measure the Zeta potential of the phosphate tailing and define the convenient values insuring the particles surfaces' best adsorption.Findings. The granular analysis has allowed us to observe a main mode represented by the fraction less than 125 μm equal to 76.77%; the weight yield of the second mode of fraction (-200 + 125) μm is about 18%; the third mode represents the coarse particle size range of a mesh of greater than 200 μm represents only 4.94% in yield. However, in the case of AERO 6493, the recovery reaches 97% in condition 150 mg/l of concentrate and 26.51% grade of P 2 O 5 . On the other hand, the flotation test with the sodium oleate shows a low recovery with good content on P 2 O 5 which reaches 30%.Originality. Since the beginning of phosphate production in Djebel Onk phosphate complex in 1965, tailings have been evacuated into the nature without any further treatment. The originality of this work lays in the recovery of phosphate in the fine slice on the one hand and the elimination of heavy metals drained in the tailing on the other hand. Practical implications.Using the alkyl hydroxamic acid with different concentrations determined in the flotation tests leads to a greatest recovery of phosphate with minimum financial charges of exploitation, transport, crushing and grinding. In result, the productivity of the Djebel Onk complex can be increased and the environment can be preserved too.

Purpose. To define the optimal physical-chemical parameters for the flotation of Djebel Onk phosphate in Eastern Algeria, for obtaining a concentrate of high quality with minimal dispenses and environment protection and using micro-flotation tests to achieve maximum recovery of the latter. Methodology. In order to achieve our purposes we used: the thermodynamic analysis method to characterize mineral surfaces and to define equilibrium pH value necessary for a complete phosphate recovery; micro-flotation tests to determine optimal quantity of sodium oleate and alkyl hydroxamic acid collector (AERO 6493) concentrations for a maximum concentrate extraction; Zeta-meter system to measure the Zeta potential of the phosphate electrokinetically to choose the suitable values insuring the best hydrophobicity of the particle surface. findings. pH equilibrium value for the "mineral-water" system makes 8.7 for Ca 3 (PO 4) 2. The maximal mineral recovery is obtained, it is about 88.6 %, at Oleate concentration till 30.44 mg/l. However, in the case of AERO6493, it reaches 86 % provided pH value equals 8.7; Zeta potential (surface charge) values-20.45 and-10.87 mV, corresponding to concentration of Sodium Oleate collector 30.44 and 75 mg/l of alkyl hydroxamic acid collector, respectively, answering the minimal necessary concentrations for a maximum apatite flotation at equilibrium pH value of 8.7. originality. The originality of this research is in the application of flotation process for the first time on Algerian phosphate ore, performed in optimal conditions (pH, collector concentrations, Zeta potential). This leads to a complete recovery of phosphate concentrate with minimal reagents dispenses and environment protection. Practical value. Application of the obtained optimal physical-chemical parameters of phosphate flotation permits a using phosphate ores rationally, obtaining a high quality concentrate with poor tailings. All this contributes to the improvement of technical-economical parameters of Djebel Onk plant and environment protection.