Geoeconomic interest of minerals assemblage of sebkha El Melah, southeastern Tunisia

Abstract

This work aimed to study the formation of salt through a progressive evaporation of sebkha El Melah brine. The precipitated salt in the case of sebkha El Melah is variable along the progressive evaporation. Weights of salt after each phase of precipitation indicate a heterogeneous evaporation process cumulating at 315 g L−1. With an increasing evaporation of El Melah brine, the number of precipitated mineral species increased. The cumulative number of species along the evaporation process reached 20, including principally: Halite (NaCl) (73–95%), epsomite (MgSO4·7H2O) (7–14%), bischofite (MgCl2:6H2O) (1%), Kieserite Mg(SO4)(H2O) (0–2%), magnesite (MgCO3) (1–4%), polyhalite (K2Ca2Mg(SO4)4,2H2O). Also, the thermodynamic theoretical modeling of the El Melah brine shows convergence with geochemical and mineralogical experimental data. At an evaporation rate of 60%, the sebkha of El Melah annually provides with 315,000 tons of salt. The majority of salt (80%) is halite. The remaining 20% contains different species having a huge economic interest. From an industrial viewpoint, our study shows that the purity of halite is guaranteed at low rates of evaporation. Evaporation between 50 and 75% produces a mixture dominated by halite. Evaporation higher than 75% needs further studies to find the mineralogical composition and the phase of each mineral precipitation. The saline system of El Melah represents a geoeconomic interest due to the cheap natural process of production, its large quantity of halite with varieties of other accessory minerals, and cheap procedure of exportation.

Geochemical, Mineralogical and Isotopic Fracturing during the Progressive Evaporation of Chott Djerid Brine (Southern Tunisia)

“…However, adequate identification of minerals essentially requires the detection of at least two or more peaks that are detectable in an XRD pattern. Recent previous studies investigated the mineralogy [64,65] and geochemistry [66] of salt in other Tunisian sebkhas based on XRD and infrared spectroscopy respectively. The samples were subsequently X-rayed to identify the mineralogy of different evaporites precipitated after each stage of evaporation.…”

Geochemistry and mineralogy of the sebkha Oum El Khialate evaporites mixtures, southeastern Tunisia

“…Tunisian sebkhas contain a high volume of natural brine, which represents enormous resources for extraction of dissolved salt (e.g., Tagorti et al, 2014;Ben Smida, 2016;Essefi et al, 2020;Essefi and Tagorti, 2021). Actually, during natural isothermal solar evaporation mineral salts may be recovered.…”