Studying the Flowability of (ZnO – CuO/ Al2O3) Catalyst through Hopper before Tableting Process Al-Khwarizmi Engineering Journal Al-Khwarizmi Engineering Journal, Vol. 5, No. 4, PP 18-24 (2009) Studying the Factors Effect on the Flowability of (ZnO – CuO/ Al2O3) Catalyst with Blending of Different Lubricants through Hopper Malek M. Mohammed * Mazin A. H. Radhi ** Ali Yasseen Nasir * * Department of Chemical Engineering/Al-Khwarizmi College of Engineering/ University of Baghdad ** Al-Rayah State Company (Received 18 March 2008 ; accepted 21 May 2009 ) Abstract One of the most important problems in tablet process is to control the flow of the catalyst through the hopper; Controlling the flow can be done either by changing the size of particles or added the different lubricant (stearic acid, starch, graphite) or blending of different lubricants. The study showed that we can control (increase or decrease) on the flow of the catalyst through the hopper by blending different lubricants for the constant percentage. The flow increasing when particles size (0.6 mm) and then decrease with or without lubricants, no effect on flow when particles size lower than (0.2 mm) with use that lubricants, and good flow on (0.4 mm) when use stearic acid and starch. Keywords: Catalyst, hopper, tablet machine, and powder blending. 1. Introduction The catalyst used in this research was (ZnO – CuO / Al2O3) which was in exyrogel phase, green color, non cohesive powder. This catalyst is calcined after tableting process to become finished catalyst Zinc – Copper over Gama Alumina (Zn – Cu / Al2O3) in gray color. Adding lubricants to catalyst is important to improve the flowing of the catalyst through the hopper and facilitating the tableting process in the tablet machine [1]. The lubricants affect the flow; compaction; and ejection behavior. Some of lubricants will decrease the flow and decrease ejection; others such as graphite will improve all the flow and ejection [2]. In the mixing of solid particles, the following three mechanisms may be involved [3]: (a) Convective mixing, in which groups of particles are moved from one position to another, (b) Diffusion mixing, where the particles are distributed over a freshly developed interface, and (c) Shear mixing, where slipping planes are formed. Lubricant levels are a delicate balance between achieving good flow and achieving good compressibility. Often, there is no magic amount of lubricant or post addition blend time that will account for variations in the excipients or the lubricant itself. By monitoring lubrication real time, physical characteristics of powder flow and tablet quality can be determined predicatively. The effect of lubricant addition to a uniform material can be clearly identified with thermal effusively. Thermal effusively relates to a material’s ability to transfer heat. When magnesium stearate coats the particles, it causes the density of the granulation blend to increase, and the heat to transfer more readily. This is measured through the increase in effusively after the lubricant is added. By monitoring the blend lubrication states in advance, operators can take preventative action taken during blending or use the information upstream and initiate appropriate actions to produce quality tablets. The lubricant blending processes is an important component in Malek M. Mohammed Al-Khwarizmi Engineering Journal, Vol. 5, No. 4, PP 18-24 (2009) 19 the development and scale-up of process applications [4]. Lubricants typically used in tableting operation are graphite, starch, talc, stearic acid and others [5]. Figure (1) [6] illustrates the blending of the particles with different lubricants which are very important in flow behavior of the catalyst, (1.A) shows the small particles with lubricants which have same particles size, (1.B) shows the medium particle sizes with lubricants without change in size, (1.C) shows the large particles with lubricant. Fig.1. Particles – Lubricants Mixture [6] The effect of lubricants on catalyst as tabulated in table below: Table 1, Effect of Lubricants on Catalyst Application [7] Lubricants Effectiveness application on catalyst Stearic acid Good Starch Not effect Graphite Excellent Magnesium stearate has disadvantage effect on flowability of powder, but when using stearic acid will give improvement in the flowability Fig. (2) [8]. The aim of the study is to show the effect of flow (ZnO – CuO / Al2O3) catalyst by using different types of lubricants (stearic acid, starch and graphite) with blending of them, to show their effects on the mass flow of the catalyst through the hopper. Lubricant content of (11 %) by weight were used. The time of mixing is greater than two minutes to ensure the lubricants blending with catalyst [9]. Fig.2. Effect Stearic Acid on Powder Flowability [8] 2. Experimental Work 2.1. Lubricants Blending In present investigation a batch blending process was used. A typical batch blending system is shown in figure (3). The basic components are a blender, one or more portable or stationary containers, and a chute to a process, e.g., a tabletting press [10]. The blending time of the lubricant was about 2 – 5 minutes [11]. Fig.3. Lubricants Blender 2.2. Catalyst Flow In this research a special hopper was used to measure the flow of catalyst (which has the same dimensions of the hopper in the "AL – Rayah State Company" which is used in the tablet machine) as shown in Figure (4). Lubricant A Lubricant B Malek M. Mohammed Al-Khwarizmi Engineering Journal, Vol. 5, No. 4, PP 18-24 (2009) 20 Fig.4. Special Hopper The mass flow rate of powder (g/s) was measured using the flow procedure: 1- Weighing the catalyst (W). 2- Allowing the catalyst to pour through the hopper, and calculate the time (t) needed for the catalyst to drain. Mass flow rate = t W ... (1) Lubricants were used as additives to the catalyst. Three different types of lubricants (stearic acid, starch, and graphite) were prepared and with blending of these types at (11 %) weight percentage, (stearic acid + starch, stearic acid + graphite, starch + graphite, and stearic acid + starch + graphite), the procedure was as follows: 1- Weigh a sample of cut used (W). 2- Calculate weigh of lubricant content percentage used (WL) which mixed it with the catalyst, for example, when used (11 %) of lubricant: LW =   W W           11.01 ... (2) 3- Mixed the catalyst with lubricant and weigh them (WM). 4- Allowing the mixture to pour through the hopper, and calculate the time (t) for the mixture to drain. Mass flow rate = t WM ... (3) Three measurements were made for the catalyst and the mean value is taken as the true mass flow rate. 3. Results and Discussion: From figures (4 – 7), it is clear that by blending of lubricants, can control the mass flow through the hopper, graphite always lowers the flow, starch promotes the flow, and stearic acid has a moderate effect (positive) on the flow. It is clear that blending starch and stearic acid will give the highest mass flow rate (comparing with the other lubricants' blending), that is due to non – cohesiveness nature of starch. Graphite lowers the mass flow rate because it is molecules form layers over lap over another layers [2]. Lubricants contribute significantly to agglomerate strength, lubricants through the reduction of particle-particle friction to allow lower void fraction and closer particle contact. Lubricants are most relevant to pressure methods of size enlargement where they may also act as mold release agents [7]. Figures (5 – 8) show that, the mass flow rate at (0.6 mm) reach to the maximum value because the size of catalyst particles increased the effect of lubricants in the flow becomes clear than the cut of small size., and then fall down because the flow depend mostly on the particles size of catalyst, the diameter of hole of the hopper which is (2 cm) is fixed and the size of particles became larger (0.72 mm), therefore, the particles were crowded and do not able to flow through hopper. Therefore the resistance of flow will be high, but generally the catalysts have good flow rate comparing with the results of figure (9). The adhesion increases with increase contact area [12]. Malek M. Mohammed Al-Khwarizmi Engineering Journal, Vol. 5, No. 4, PP 18-24 (2009) 21 0 20 40 60 80 100 120 140 160 180 200 0 0.2 0.4 0.6 0.8 1 1.2 Average Particles Diameter (m)×10 3 M a s s F lo w r a te ( k g /s )× 1 0 3 Stearic acid Starch Stearic acid & Starch Fig.5. Effect Particles Sizes on Flow With Blends (Stearic Acid & Starch) 0 20 40 60 80 100 120 140 160 180 0 0.2 0.4 0.6 0.8 1 1.2 Average Particles Diameter (m)×10 3 M a s s F lo w r a te ( k g /s )× 1 0 3 Stearic acid Graphite Stearic acid & Graphite Fig.6. Effect Particles Sizes on Flow with Blends (Stearic Acid & Graphite) 0 20 40 60 80 100 120 140 160 180 200 0 0.2 0.4 0.6 0.8 1 1.2 Average Particles Diameter (m)×10 3 M a s s F lo w r a te ( k g /s )× 1 0 3 Starch Graphite Starch & Graphite Fig.7. Effect Particles Sizes on Flow with Blends (Starch & Graphite) 0 20 40 60 80 100 120 140 160 180 200 0 0.2 0.4 0.6 0.8 1 1.2 Average Particle Diameter (m)×10 3 M a s s F lo w r a te ( k g /s )× 1 0 3 Stearic acid Starch Graphite Stearic acid & Starch & Graphite Fig.8. Effect Particles Sizes on Flow With Blends (Stearic Acid & Starch & Graphite) 0 20 40 60 80 100 120 140 160 0 0.2 0.4 0.6 0.8 1 1.2 Average Particles Diameter (m)×10 3 M a s s F lo w r a te ( k g /s )× 1 0 3 Fig. 9. Effect the Particles Sizes on the Flow (Without Lubricants) Figures (10 – 13) show that the lubricants blend was improved the flowability of catalyst before distribution comparing to the previous batches containing lubricants [13]. . (Stearic acid + Starch) Stearic acid Starch 167.609168.038 175.8 100 110 120 130 140 150 160 170 180 Mass Flow rate (kg/s)×103 Fig. 10. Mass Flow Rate of Blends (Stearic Acid & Starch) Lubricants for Catalyst Before Distribution Malek M. Mohammed Al-Khwarizmi Engineering Journal, Vol. 5, No. 4, PP 18-24 (2009) 22 . (Stearic acid + Graphite) Stearic acid Graphite 112.784 168-038 146.7 100 110 120 130 140 150 160 170 180 Mass Flow rate (kg/s)×103 Fig.11. Mass flow rate of Blends (Stearic Acid & Graphite) Lubricants for Catalyst before Distribution . (Starch + Graphite) Starch Graphite 112.784 167.609 135.6 100 110 120 130 140 150 160 170 Mass Flow rate (kg/s)×103 Fig.12. Mass flow rate of Blends (Starch & Graphite) Lubricants for Catalyst before Distribution . (Stearic acid + Starch + Graphite) Stearic acid Starch Graphite 112.784 167.609168.038 160.5 100 110 120 130 140 150 160 170 Mass Flow rate (kg/s)×103 Fig.13. Mass Flow Rate of Blends (Stearic Acid & Starch & Graphite) Lubricants for Catalyst before Distribution 4. Conclusions 1- The flow of catalyst (with or without lubricants) through the hopper depends upon the particles size, the flow increases with particles size until (0.6 mm) and then decrease. 2- The flow of catalyst through the hopper can be controlled by blending different types of lubricants, e.g. (stearic acid, starch, and graphite). 3- The lubricants (stearic acid, starch, and graphite) show low effect on flow when particles size lower than (0.2 mm). 4- Stearic acid and starch have good lubricant properties when particles size more than 0.4 mm. Nomenclature t The time of drain catalyst (s) W Weight of catalyst (kg) WL Weight of lubricant percentage (kg) WM Weight of catalyst – lubricant mixture (kg) 5. References [1] Little, A. and Mitchell, K. A., "Tablet Making", 1963. [2] Komarek, K. R., "Selection binders and lubricants for agglomeration processes", Chemical Engineering, Vol. 74, December 4, P. 154 – 155, 1967. [3] Coulson and Richardson, "Chemical Engineering" Vol. 2, P.30, Butterworth- Heinemann/ 2002 (5 th Ed.). [4] "Nir & Blend/Dose Uniformity Testing", Meeting FDA requirements, June, 2005. [5] Jon, E. Browning, "Agglomeration: growing large in application and technology", Chemical Engineering, Vol. 74, December 4, P. 151 – 153, 1967. [6] Hardo, P. J., "Manufacturing by Selective Laser Sintering", by internet. [7] J. C. Williams, and T. Allen, "Handbook of Powder Technology", Vol. 1, "Particle Size Enlargement", Elsevier Science Publishers, 1980 [8] Cunningham, C. R. and Scottergood, L. K., "Optimizing Lubricant Usage in Direct Malek M. Mohammed Al-Khwarizmi Engineering Journal, Vol. 5, No. 4, PP 18-24 (2009) 23 Compression Hydrochlorothiazide Formulation Containing a Plastically Deforming Excipient". [9] Coulson and Richardson, "Chemical Engineering" Vol. 2, P.33, Butterworth- Heinemann/ 2002 (5 th Ed.). [10] Kirk – Othmer "Encyclopedia of Chemical Technology", Vol. 19, John Wiley & Sons, Inc./ 2002 (4 th Ed.). [11] Mukesh C. Gohel, Rajesh K. Parikh, Bansari K. Brahmbhatt, and Aarohi R. Shah, AAPS Pham. Sci. Tech., February 8, Article 13, 2007. [12] Lieberman, A., Chemical Engineering, April 10, P. 209 – 218, 1967. [13] Charles R. Cunningham, and Laura K. Scattergood, American Association of Pharmaceutical Scientists, October, 2000. 24- 18، صفحت 4، العذد 5مجلت الخوارزمً الهىذسٍت المجلذ مالك مصطفى محمذ (2009) 24 دراست العوامل المؤثرة على اوسٍابٍت العامل المساعذ (Al2O3  (ZnO – CuO/ مع مسج مسٌتاث مختلفت خالل القمع *علً ٌاسٍه واصر** مازن عبذ الهادي راضً* مالك مصطفى محمذ جبمعت بغذاد / كهيت انهىذست انخىارزمي/ قسم انهىذست انكيميبئيت االحيبئيت * شركت انرايت انعبمت سببقب ** الخالصت انسيطرة عهً انجريبن يمكه ان يعمم امب بخغيير حجم , احذي اهم انمشبكم في عمهيت انكبس هي انسيطرة عهً جريبن انعبمم انمسبعذ خالل انقمع انذراست بيىج بأوىب يمكه ان وسيطر . او مسج مسيخبث مخخهفت (انىشب و انكرافيج, حبمض انسخريك)جسيئبث انعبمم انمسبعذ او أضبفت انمسيخبث انمخخهفت ( مم0,6)انجريبن يسداد عىذمب حجم انجسيئبث . عهً جريبن انعبمم انمسبعذ خالل انقمع بمسج انمسيخبث انمخخهفت نهىسب انمئىيت انثببخت (زيبدة او وقصبن) وجريبن جيذ في , مع اسخعمبل حهك انمسيخبث ( مم0,2)ال حأثير عهً انجريبن عىذمب يىخفض حجم انجسيئبث عه , وبعذ رنك يخىبقص مع او بذون انمسيخبث . عىذ اسخعمبل حبمض انسخريك وانىشب ( مم 0,4)