Hardness Removal of Industrial Water by some Clays in Sudan

Abstract

The industrial water is the water used to generate steam to be used in many industries. The tap water contains salts, minerals, ions, organic material and micro organisms. The ions of Ca+2 and Mg+2 are most common ions present in the tap water; they make a problem of hardness and scales deposit on the electrical pipes of the boilers. The scales are building up through time to the limit of total coverage of the pipes and even materials that can make unavoidable blocks. The mechanical removing of the salts result into many difficulties; moreover, the exploitation of energy with poor efficiency of the generation of the steam. The general practice used industrially is that, they use HCl to remove scales, in addition to small amounts of organic materials to clean the pipes after mechanical removal of the deposits. Here in this research we adopted five types of earths available in the Sudan. They are: West Nile Clay, East Nile Clay, Blue Nile, Soba, and in addition to famous Jurdiga. By treating the earths with 0.01, 0.02, 0.05, 0.07, 0.1 and 0.2M NaOH and with the same concentrations of KOH. Usually 50g of these earths were treated with 150cm3 of the alkali solutions. The treated clays were calcined to 400⁰C. A pilot plant was developed to test the efficiency of large scale production of soft water by passing tap water continuously through the treated clays. The experimental part used the ordinary glassware, for activation, then the technique of grain size distribution. The flame photometer, the X- ray fluorescence, the X- ray diffraction were used for samples characterization, in addition to wet chemical analysis. The statistical product and service solution (SPSS) was used to evaluate the results obtained from the laboratory. The following results were obtained according to the efficiency of hardness removal by different alkali concentrations. For NaOH the efficiencies were in the range 50% to 80% for Jurdiga sample, then West Nile Clay in the range18% to 70%, East Nile Clay 13% to 70%, Blue Nile 8% to 62% and West Soba 18% to48%. The pilot results gave efficiency of scale removal of 40% when (250 g earths were treated with 0.1M NaOH ), to give 18 liters of soft water; while the calcined samples gave only 8 liters. The SPSS results showed that the independent sample T- test prove that there was no difference in using NaOH or KOH. The III difference is that in concentration of the base as given by ANOVA. The chemical analysis of the samples showed that the samples were aluminium silicates. The results of chemical analysis were reviewed by X- ray fluorescence of same constituents while the X- ray diffraction showed the dominant constituents of hematite, of West Nile clay while feldspar of East Nile clay, Blue Nile and Soba sample, while Jurdiga was plagioclase feldspar. The grain size distribution ranges from silty clay to fine sands of West Nile clay, East Nile clay and Blue Nile samples respectively. 50% silt and 50% fine sand of Soba sample. Usually it was noticed that the sample contains clays and feldspar was the best one. The used earths contain amounts of Ca+2 and Mg+2 as waste products, then for further research work, the waste could be moulded, calcined and material impact tested as ceramic bricks. The research findings could be directly reflected to the industries to solve the problems of hard water and to save energy with high degree of safety to the boilers and the workers. It is the utilization of our local resources using science innovation.