Thermal Beneficiation of Kaolin Clay in the Removal of Potassium Ion

Transcription

1 International Journal of Material Science Innovations (IJMSI) 2(5): , 2014 ISSN Academic Research Online Publisher Research Article Thermal Beneficiation of Kaolin Clay in the Removal of Potassium Ion Mahmud H. 1, Otoikhian S.K 1, Anakhu A.E 1, Nworie C.E 1, Okpugwo E 2 1 Department of Chemical Engineering, Auchi Polytechnic, Auchi 2 Department of Surveying and Geoinformatic Technology Auchi Polytechnic, Auchi Corresponding author lawekebafe@gmail.com Corresponding Tel.: A b s t r a c t Keywords: Kaolin clay, Potassium ion, Calcinations. The removal of potassium ions present in kaolin clay thermally was investigated. This was done by calcinating the samples at a range of temperature and time. The results revealed that out of the mg/L of potassium ions initially present at 800 o c (o min), only 1.26mg/ L potassium ions was left haven calcinated the clay at 1200 o c (90min), which shows good removal of potassium ions from the clay sample. Investigation was also carried out considering varied weight sample and it revealed that both temperature and weight show significant impact in removing potassium ions from kaolin clay samples. Accepted:11October 2014 Academic Research Online Publisher. All rights reserved. 1. Introduction Kaolin clay is one of the most abundant natural mineral resources which are found deposited in significant quantities in states including; Bauchi, Katsina, Ondo, Ekiti and Enugu in Nigeria. Kaolin clay occurs either as a residual or sedimentary deposits and sometimes associated with impurities such as Ti0 2, Fe 2 0 3, and organic matter, often grouped with fire clay because of their excellent refractory native [1,2]. Kaolin has found various uses in many industries due to its unique chemical and physical characteristic. Among such are ceramics, especially in the production of zeolite catalyst in the petroleum refinery [2]. Clay which has kaolinite minerals (called kaolin) which was used in this study is deposit in commercial quantities in kankara area of Katsina State. Thermal beneficiation of kaolin clay in the removal of potassium ion involves the calcining of the kaolin clay at various temperature, time interval and variation in the weight of clay been calcined. The

2 removal of potassium from kaolin clay has various importance such as in the production of zeolite. The preliminary work was the calcining of the samples in the furnace at different time interval. The calcined clay was then digested into solution using nitric acid and sulphuric acid, which was then analysed, using the Atomic Absorption spectroscopy (AAS). The objective of this work is to determine how heat can remove potassium ions from the kaolin clay. The beneficiation of kaolin clay can take different forms: Selectivity Mining which is use to select the best available deposit for subsequent process and the deposits are chosen based on the desired component of the clay. Dry Process Involves crushing, grinding and severing clay material for industrial use. Wet Process is done by the mastication of clay lumps in a plug mill, followed by dispersion process. Thermal Process which is the beneficiation of the kaolin clay is carried out by calcaining the clay at reactively high temperature [3]. Kaolin clay is a natural source of the synthetic zeolite (x&y) and the potassium ion in kaolin clay have some advance effect during the production of some zeolite (zeolite y and others), so we need to remove the potassium present in the clay. This removal can be effective by the application of heat to the clay and regulation of time and temperatures. The effect of heat on kaolinite indicates that after the removal of adsorbed water at over 100 o c, kaolinite decomposes above 450 o c losing its hydroxyl groups as water when heated, kaolin types of clay undergo several transition in air. The first of these takes place at about 550 o c and produce the disordered metakaolin phase by an endothermic dehydration reaction. The metakaolin is then stable to about 925 o c, where it rearranges to see defect alumination silicon spinal [3,4]. Fig.1: Reaction of Kaolin clay at different temperatures *Note: As indicated in the equations above, silica is liberated at every stage of the transition. 125 P a g e

3 The potassium ions serve as impurity, which in the gel form; inhibit the formation of zeolite y and x and zeolite p crystals instead. This zeolite (y & x) serves as an important catalyst in the refinery today. 2. Experimental procedures 2.1. Materials and mix design The main material for this study is the kaolin clay, which was calcined using the furnace, ceramic crucibles, mortar and pestle, timer, tong and dessicator. The kaolin clay also undergo digestion process with the help of some laboratory equipment like, measuring cylinder, funnels, filter paper, distilled water and reagent like nitric acid, sulphuric acid, heating mantle and weighing balance. Atomic Absorption spectrometry (AAS) was used to measure the amount of potassium ions present in the clay. 2.2 Heating schedule of the furnace The furnace heating schedule was measured to know how long it takes for a particular temperature to be reached; before timing the sample inside furnace at a particular temperature. And it was done by taking record of the various rises in temperature with time. 2.3 Clay Beneficiation The clay was dried, grinded, and sieved using a mesh size of 75 micro to obtained finer particle in suspension. 2.4 Clay Calcination The clay samples were calcined at various temperature and time intervals. The calcinations process was carried out in two batches. In the first batch a 20g of the clay samples were calcined at 600 o c o c for 0-90mins respectively. The calcined clay were then digested and analyzed using the Atomic Absorption spectrometry (AAS) to get the concentration of potassium ion left in the clay samples after calcination. In another batch at 800 o c, different samples weights (4g-16g) were treated as show above for varying time (0 60min) 2.5 Analysis of kaolin clay 1g of the calcined clay samples were weighed and transferred into a beaker. 5ml of H 2 SO 4, 15mg of HNO 3 were added and stirred. The solution was then heated for 30mins. The heated samples were then filtered into 100mg/L volumetric flask. Distilled water was used to make it up to 100mg/L in the volumetric flask. The filtrates were then taken for the AAS analysis. 126 P a g e

4 3. Results and discussion The results of AAs analysis, showing the concentration of potassium ions left in the calcined clay for at various heating temperature and time are as presented in table 1-5. While the heating schedule of the furnace result is shown in table Effect of temperatures and time on the removal of potassium ions from the kaolin clay Temperature and time have great effect on the removal of potassium ions from the kaolin clay. The calcinations process was done in two batches. In the first batch of the experiment, a flat weight of 20g was considered at various temperatures and time at 600 o c, the 0mins is actually 24mins as shown in the heating schedule table. It was also observed that at 600 o c, the amount of potassium present in the samples are 2.327mg/L, 3.858mg/L and 11.23mg/L at 24mins, 39mins, 94mins and 114mins, which shows that there is an increase in the concentration of potassium ion left in the sample with time. This implies that at 600 o c, we have generation of potassium (i.e. the bond existing between potassium and the clay is been broken, to release potassium from the clay) which result to an increase of potassium present in the clay at that temperature (600 o c) showing the beginning of the removal because the potassium has to be detach from the kaolin clay to enable the removal to become effective [4, 5, 6]. Therefore, consideration of 800 o c was done and the values are shown in table 2, which brings about the removal of potassium from the clay samples. Calcination of the clay at 800 o c in 0min shows mg/L potassium to be left in the clay. This implies that, the generation of potassium still continuous until 800 o c, before the removal starts during the consideration of times: 60mins, 75mins, 105mins, there was reduction of potassium left in the clay, as shown in the table 2. Also other temperatures (950 o c, 1000 o c, 1200 o c) were also considered and there was mass reduction of potassium present in the clay samples [7, 8] as shown in Tables 3, 4 and 5. Table 1: AAS Analysis for the calcined clay at 600 o c for 20g of the sample P a g e

5 Table 2: AAS Analysis for the calcined clay at 800 o c for 20g of the sample Table 3: AAS Analysis for the calcined clay at 950 o c for 20g of the clay Table 4: AAS Analysis for the calcined clay at 1000 o c for 20g of the clay P a g e

6 Table 5: AAS Analysis for the calcined clay at 1200 o c for 20g of the clay Table 6: Heating schedule of the furnace Temperature C Time (mins) Table 7: AAS Analysis for the calcined clay at 800 o c for 8g of the clay P a g e

7 Table 8: AAS Analysis for the calcined clay at 800 o c for 12g of the clay Table 9: AAS Analysis for calcined clay at 800 o c for 16g of the sample Effect of variation in weight In the second batch of the work, variation in weight of the sample was also considered. These also affect the removal of potassium ion from the clay samples. So 800 o c was considered as a constant temperature to enable the variation weight 8g, 12g and 16g. The result for the weight variation is as presented in table 7, 8, and 9. Also in comparison, it shows that an increase in weight, result to a decrease in the concentration of potassium present in the clay. 4. Conclusion Based on the work, the following conclusion can be made. I. Calcinations of clay at 600 o c, shows that there was generation of potassium from the clay to enable easier removal of potassium to occur. II. While calcinations of 800 o c, 950 o c, 1000 o c and 1200 o c indicate the removal of potassium ions taking place. But at 1200 o c, there was an excellent removal of potassium ions from 130 P a g e

8 the clay, which is almost zero i.e. almost the whole potassium present in the clay sublimed i.e. started from mgll and left with about 1.261mgk. III. Lastly consideration was also done on variation of the weight and it shows that weight also have effect on the removal of potassium ion. References [1] Breck O.W. Zeolite Molecular Sieves, Chemistry and Use: Wiley Interscience publications, New York, 1974: [2] Mc Graw Hill Encyclopedia of Science and Technology, Mc. Graw Hill Inc., New York 1982; 3.5: [3] Kirk O. Encyclopedia Chemical Technology, 3 rd Edition Supplementary, John Wiley and sons Inc., U.S.A 1984: [4] Okibe, O.C, Kinetic Modeling of De Alumination of Metakaolin Clay using sulphuric acid, Research product (Unpublished), Department of Chemical Engineering A.B.U, 1999: [5] Oloro Elizabeth Funmilayo, Determination of Activation Energy Involved In The Dealumination of Kankara Clay, Research Project (Unpublished), Department of Chemical Engineering, A.B.U. 1999: [6] Perry, Z.H., and Chilton, C.H. Chemical Engineers Handbook, 5 th Edition, Mc Graw Hill Book Co. London, 1974: [7] Velde, B.V. Introduction to clay Minerals, 3 rd Edition, Chapman and Hall London, 1992: [8] Vogel Arthur I. Quantitative Inorganic Analysis Including Element Instrument Analysis, 3 rd Edition, London, 1994: P a g e