Production of Liquid Alum Coagulant From Local Saudi Clays

Abstract

This study was carried out to investigate the use of local clays extremely abundant in the Kingdom for production of liquid alum. Local kaolinitic clay containing 29.4% Al 2 O 3 was ground, activated by calcination and treated with sulfuric acid solution to extract alumina. In the activation step, the effects of grain size of clay, temperature and period of calcination on the extraction of alumina and iron oxide are investigated. Leaching experiments were conducted using the stoichiometric requirement of 40 wt. % H 2 SO 4 for one hour under boiling conditions. Clay samples of particle size ranging from 8 to 200 mesh standard Tyler screens, calcined at different temperatures ranging from 450 to 1000 o C and for different periods ranging from 15 to 180 minutes were used. The results revealed that 90.9% of Al 2 O 3 can be extracted when using-65 mesh clay, calcined at 700 o C for one hour. Experiments on the effect of acid concentration on alumina extraction from clay under the above conditions indicate that 40 wt.% acid is the recommended as it gives high extraction of alumina and at the same time results in free flowing properties of the reaction mixture. Leaching experiments were performed to investigate the effects of acid to clay ratio (50 to 120%) and leaching period (0.25 to 3 hrs) on alumina extraction. The results indicate that 88.6% of Al 2 O 3 could be extracted when using 88.1% of stoichiometric requirement of 40 wt.% acid for two hours leaching period under boiling conditions.

Extraction of Alumina from Local Clays by Hydrochloric Acid Process

“…The chemical composition of the clay sample is given in Table 1. The analysis of local clay was done at the Chemical & Materials Engineering Department, College of Eng., KAU [22] . Table 1.…”

“…A muffle furnace (Carbolyte) with a maximum temperature of 1200 o C was used. The heating is carried out at 700 o C for 1 h to activate the clay before acid treatment, which is reported in some previous work to be the recommended conditions for activation of local Saudi kaolinitic clays [22,23] .…”

Potentials of fabricating porous ceramic bodies from kaolin for catalytic substrate applications

“…Though it usually contains a variety of structural defects, the structural orderliness of these kaolinites tend to influence many of the properties which are exploited industrially. Kaolinite and more specifically ordered kaolinite have been found to be of immense application in alum and alumina production (Al-Zahrani and Abdel-Majid, 2004;Hosseini et al, 2011), ceramics, zeolite catalysts, catalyst supports for auto-exhaust purification, adsorbents for heavy metals and currently in catalysis, to mention a few (Murray, 2000(Murray, , 2007Bergaya et al, 2006;Murray and Kogel, 2005;Churchman et al, 2006;Adams and McCabe, 2006).…”

Synthesis and characterization of silica nanoparticles from clay

“…Bentonite clay is a potential source of silica, which contains smectite as a main clay mineral. As alumina component is present in clays along with silica, a range of acid and alkali hydrometallurgical methods are employed to isolate them from each other [16][17][18][19]. Usually acids are used for the processing of clay rather than alkalis [20] and HCl is preferred over other acids due to the easy separation of filtrate from the residue [21].…”

“…For effective removal of alumina from clays, calcination is a critical step; solubility of alumina increases after thermal treatment in the temperature range of 500-900 • C [22,23]. Previously, kaoline clay was studied for the production of aluminum sulfate and it was found that heating the clay to 700 • C for 1 h followed by acid leaching with sulfuric acid (H 2 SO 4 ) were the optimum conditions to extract alumina [18]. In another work, removal of alumina component from kaoline to produce pure alumina was studied and the recommended process involved the calcination of clay at 600 • C for 1 h followed by leaching with HCl.…”