Title of Invention

"A PROCESS FOR PREPARATION OF HIGH VALUVED ŋ-ALUMINA FROM ALUMINIUM DROSS"

Abstract

A process is disclosed where treatment of waste aluminium dross, comprising alumina, aluminium, silica, Fe2O3, NaCI, KCI, etc., with sulfuric acid has been performed to take out preferentially alumina value into the solution as aluminium sulfate. More than 90% alumina recovery efficiency is found. Washing of aluminium dross is essential to achieve higher recovery. The aluminium sulfate solution obtained after sulfuric acid dissolution of dross is hydrolysed to obtain amorphous aluminium hydroxide. In this case ammonia has been taken as the hydrolyzing precipitant. Amorphous aluminium hydroxide is further dehydrated at 900°C to obtain -alumina, which is considered as good activated alumina.

Full Text

The present invention relates to a process for production of -alumina from waste aluminium dross by sulfuric acid dissolution method. The invention largely falls in the field of material preparation from secondary sources. The secondary aluminium dross is generated due to natural oxidation of molten aluminium on the surface of the melt. This dross is remelted by adding salts to recover residual metal part leaving behind waste aluminium oxide dross containing lower amounts of metal. This dross is also a very toxic material and while stock pilling it leaches out toxic metals such as Na, K, etc. into the ground water. The above process would therefore address both the problems of environment concern and stock piling of waste aluminium dross. Prior art details: Disposal and recycling of dross produced during aluminium melting is a worldwide problem. Majority of dross is disposed off in landfill sites or stock piled, which could result in leaching of toxic metal ions into ground water causing serious pollution problems. In addition to this when aluminium dross comes in contact with water it emits harmful gases such as NH3, CH3, PH3, H2, H2S, etc. In India, a rough estimate shows ~75,000 tons of dross is generated annually and most of it is used for making crackers, impure chemicals and low quality refractory bricks or stock piled due to want of proper treatment options. The aluminium dross is considered as waste material after recovering back the residual metal part. Residual metal part in the dross is removed by remelting it by adding salt flux to minimize the oxidation. In majority of the cases salt bath is used to maximize the recovery of aluminium. By this process though oxide generation is less the dross becomes very toxic because it is treated with salts and makes the disposal and recovery of aluminium more complex. The increasing demand of valuable materials and environmental standard enforcement has forced the development of suitable treatment facilities for industrial wastes. Further, for sustainable development, replacement of primary resources with secondary resources has also become very essential. The conventional dross oxide treatment consists of grinding the dross, sieving to recover the metal value and water leaching to dissolve the salt in water from residue oxide. The salt is recovered back by filtering and evaporation technique. The residue is calcined consisting primarily alumina and spinnel (MgO.Al2O3). The market available for the residue oxide is ceramic, refractory and to certain extent cement. In another similar process where aluminium is mechanically separated from oxide part and the remaining oxide fines are blended into a product that can be used for steel industries. In recent times Portland cement industries is using certain quantities of alumina for the production of cement. As the requirement of aluminium oxide is around 5%, many producers in US utilize this dross oxide for production of cement. Various processes are available which utilized mostly Rotary furnaces or plasma furnaces for treatment of dross. In these cases it is aimed to maximize the metal recovery and to prevent further oxide formation. The residue of aluminium dross oxide is further treated for use in various industrial products or land filling. Actually a very less literature is available where residue aluminium oxide treatment has been highlighted. Symposium on Recycling, Waste Treatments and Clean Technology, Vol. II, REWAS, (1999) 995, wherein the dross was leached with NaOH to extract the aluminium as sodium aluminate and then precipitated in the form of aluminium hydroxide. The residue in the leaching was roasted to oxidize the remaining metals. During roasting most of the metal changed to their oxides. This roasted oxide is used for making high castable refractories by mixing with aggregates and alumina cement. In this process only aluminium is recovered as NaOH does not react significantly with oxide of aluminium and thus the major quantity of oxide is roasted to other products. Washing of NaOH solution is very difficult and soda may end up with refractory bricks because soda is a detrimental for such application. Reference may be made to E.A. El-Katatny, S.A. Halaway, M. A Mohamed, M.I. Zaki; Powder Technology 132 (2003) 137, wherein the aluminium is recovered from dross in NaOH solution and precipitated out aluminium hydroxide from it. This powder is then activated at 600°C to obtain Y-AI2O3. Various studies have been undertaken where H2SO4 is utilised for manufacture of aluminium sulphate. Generally bauxite or aluminium hydroxide is used to manufacture aluminum sulphate. In most of the works aluminium sulphate produced is having various contaminants, thus making the sulphate impure. Reference may be made to A.M. Amer; Journal of Metals, November (2002) 72, wherein the author produced two types of alums (aluminium sulphate) by dividing the alumina leaching process in two steps. In the first case leaching was carried out with dilute H2SO4 to remove impurities and in the second process alumina was extracted from the purified dross tailings using concentrated H2SO4. The two products obtained are aluminium sulphate alum and ammonium aluminium sulphate alum. Reference may be made to L.W. Garret; U.S. Patent, 4,337,228, 29th June (1982), wherein aluminium sulfate was prepared for water treatment and paper making industries from by-product aluminium oxide. Reference may be made to A. Durward and D.S. Arthur; U.S. Patent No. 4,320,098, 16th March, 1982, wherein aluminium sulfate was prepared with H2SO4 treatment between 20-135 psia. In both the above cases aluminium sulfate produced have contaminated impurities and in 2nd case leaching studies were carried out under pressure conditions. In India no significant effort has been made to reclaim the dross for valuable use. The dross is treated in India mostly in unorganized sectors for preparation of impure chemicals, crackers and castable refractories. In the present study emphasis has been given to leach out the alumina value in sulfuric acid media. With the addition of sulfuric acid, aluminium as well as other metallic sulfates will be forming, unless the reactions are controlled strictly. Nevertheless, some of the other oxide component will be unreacted. Certain amount of aluminium part in the dross will also react with sulfuric acid to form aluminium sulfate. Aluminium sulfate formed in the acid treated solution is neutralised with ammonia to form aluminium hydroxide, which is further treated to obtain activated alumina. The impurities present in the dross will generally enhance the activity of the alumina Based on the above details and drawbacks, it has been found that a need for development of complete process for treatment of dross to a high valued product is necessary for optimum utilization of dross. In this connection a high valued product such as activated alumina namely n-alumina was produced. OBJECTIVES OF THE INVENTION The main object of the present investigation is to provide a suitable method for preparation of active n-alumina from aluminium sulfate solution obtained by HaSOn dissolution of aluminium dross, which obviates the drawbacks of the hitherto known prior art as detailed above. Another object of the present invention is to provide the option to utilise the aluminium dross rather than stock piling and creating pollution hazard. Yet another object of the present investigation is to provide a washing step to collect salts containing NaCI and KCI. Yet another object of the invention is to provide a process for obtaining high valued product through an efficient dross treatment procedure. Yet another object of the present invention is to provide an efficient sulfuric acid dissolution process Summary of the present invention Processing of aluminium dross is one of the most challenging tasks because of its toxic nature. Dross processing in India has not taken up very seriously so far. The process developed here for the treatment of aluminium dross is unique in nature. The novelty of the present process is that n-alumina a high valued product can be produced from waste aluminium dross. So far the treatment options available mostly aimed to optimize the recovery of metal part from oxide part and rest was land filled. There are other options where oxide part is further heat treated to obtain oxides, which may be used as abrasive materials, ceramic or refractory materials. The carbon present in the dross is removed as COa when treated at higher temperatures. Some other processes where sulphuric acid is used to treat dross produced impure aluminium sulphates because either it will be contaminated with iron hydroxide or most of the leachable alloying elements will ultimately end up with aluminium sulfate. In the present case domestic aluminium dross is treated for developing different process options to obtain a high valued product. The dross used here is obtained from indigenous source and contains mostly a-AI2O3, magnesium aluminate, metallic aluminium, silica, sillimanite, FeaOs, NaCI, KCI etc. The bigger particles in the dross containing mostly aluminium are separated from the finer alumina part by screening. In the present case finer part containing aluminium oxide rich fraction is processed further. The process developed here consists of various inventive steps such as (1) washing of dross, (2) leaching of original and washed dross, (3) filtration of leached slurry to separate out aluminium sulphate solution and residue, (4) removal of iron from the leached solution by controlling the pH at ~4 by aqueous ammonia, (5) precipitation of aluminium hydroxide from leached solution by increasing the pH up to 7.0 (6) preparation of activated alumina such as n-alumina by dehydration and desulfurisation at 900°C. The residue obtained after filtration can be used as abrasive material or may be further treated for using in various industrial products such as castables. As a result, the dross which is generally stockpiled or used as ingredient for impure chemicals and crackers, can be totally utilized and the environmental problem can be minimized. In the present study a flow sheet has been developed where initially water soluble salt is recovered by water washings. H2SO4 dissolution process has been optimized with original dross and found that 30% acid (by vol.) at 10% pulp density of dross would leach out 88% AI2O3. It has been found that maximum recovery of ~92% is possible with water washed dross under similar conditions. While 15% acid (by vol.) showed recoveries of 84%, 80% and 71% for washed dross, washed & dried dross and original dross containing salts respectively. Presence of salts restricted the alumina recovery. 15mL acid is the stoichiomeric amount required for 10g of dross considering 6.5g alumina and other additional impurities such as iron, etc. Extra acid in the leach liquor may be neutralized with fine dross powder separately kept prepared for the purpose. One hour leaching time is found to be sufficient to obtain major recovery. From the experimental results the optimized solids concentration is found to be around 10%. 15% acid with 10% solids concentration may be used for commercialisation purpose by sacrificing 6-8% alumina recovery. This will be important consideration during process cost estimation. The aluminium containing leached solution is further treated with aqueous ammonia to obtain amorphous aluminium hydroxide. This aluminium hydroxide is heat treated at 900°C to obtain n-AbOa, which is a high valued activated alumina. The n-AbOs conversion has taken place only after desulfurisation at 900°C. SUMMARY OF THE INVENTION Accordingly the present invention provides a process for the preparation of high valued n-alumina from aluminium dross, the said process comprising the steps of: (a) washing aluminium dross with wash water, at a temperature in the range of 25 to 80°C to remove the water soluble salts, (b) reacting the above said washed aluminium dross with 15 to 70% aqueous sulphuric acid, at a temperature ranging from 75 to 95°C to obtain the aluminium sulfate solution, (c) reacting the above said resulting aluminium sulfate solution with about 10% aqueous ammonia solution to precipitate out aluminium hydroxide, at a pH ranging from 5 to 7, at a temperature ranging from 20 to 80°C followed by drying at about 80°C to obtain the dried aluminium hydroxide, (d) heating the above said dried aluminium hydroxide at a temperature in the range of 200 to 1000°C to obtain the desired non-toxic n-alumina . In an embodiment of the present invention the temperature used for washing of aluminium dross with wash water is in the range of 60 to 80°C. In yet another embodiment the % aqueous sulphuric acid used in step (b) is in the range of 30 to 50%. In yet another embodiment the aqueous sulphuric acid used in step (b) is 30% to obtain the maximum recovery of AfeOs of about 92%. In yet another embodiment the aqueous sulphuric acid used in step (b) is 50% to obtain the maximum recovery of AbOa of 94%. In yet another embodiment the concenterate of aluminium dross obtained in step (b) in aqueous sulphuric acid is in the range of 5% to 20%. In still another embodiment the concentration of aluminium dross used is 10% for the maximum recovery of AI2O3 of 91%. DESCRIPTION OF THE INVENTION Aluminium dross is a waste material obtained from aluminium melting plants whose composition differs due to the various alloying elements used during melting. The dross used in this work contains ~65% alumina, 4% SiO2 and oxides of Mg, Ca and Fe along with some salts such as NaCI and KCI. This dross contains bigger particles of 2-5 mm in size, which are mostly aluminium or its alloy and the finer fractions are mostly alumina (AI2O3) and less than 5% of aluminium. Screening of the above material is undertaken to separate out the aluminium part from the oxide. The The analysis of which is given in Table 1. Philips x-ray fluorescence (XRF) analytical equipment is used for dross analysis. The x-ray diffraction (XRD) analysis is carried out in a Philips powder diffractometer model PW 1830 x'pert system. The carbon and sulfur is analysed using LEGO instrument. The XRD analyses of the dross showed the presence of a-AfeOa, CaF2, metallic aluminium, MgAl2O4) Fe203, CaO, carbon, sulfur and salts like KCI and NaCI. Table 1. Major (Table Removed)In the 1st step of process development the aluminium dross was washed with water to remove water soluble salts such as NaCI and KCI. Around 5-6% salt is removed from the dross by hot water washing. The dissolution studies of aluminium dross in H2SO4 are carried out by changing various parameters such as acid concentration, solid dross concentration, reaction time etc. The dissolution experiments of dross in H2SO4 medium are carried out in a flat bottomed glass reactor at a temperature of 95°C with stirring by a magnetic paddle and the reactor is placed on a Remi make hot plate cum magnetic stirrer. The dissolution reaction is exothermic and attains temperature of 80-85°C without any input of heat from out side. The hot plate is utilized to maintain the temperature around 95°C. In each case 10 g of dross is taken unless otherwise jpecified. Each experiment is carried out for 3 h followed by aluminium analysis of :he leached liquor. Kinetic study is also carried out up to 3h only. The alumina analysis is carried out by conventional EDTA-ZnSO4 method. The sulfuric acid treated liquor obtained after filtration of the slurry contains 10-12 gpL of AfeOa as aluminium sulfate. This liquor also contains considerable amount of iron i.e. around 250-300 rng/L The aluminium present in the liquor is precipitated out as aluminium hydroxide using ammonia as the hydrolyzing precipitant. Drop wise addition (5 mL/min.) of dilute ammonia to the liquor resulted in precipitation of aluminum hydroxide rich in water content (Al2O3: 42%, H20 & S04, 58%). Aluminium hydroxide produced is amorphous in nature as revealed by x-ray diffraction data. Generally while precipitating out alumina in the liquor iron also gets precipitated out. This iron imparts brownish colour to the precipitate. Iron precipitates out earlier than aluminium does. Iron is started precipitating out as hydroxide at pH 3.8 to 4.0. This iron hydroxide is removed by filtration and the filtrate is further processed to get white aluminium hydroxide powders that started precipitating out at pH around 5.0. Preparation of activated alumina is undertaken by heating the aluminium hydroxide material at various temperatures. The temperatures varied between 200 to 1000°C. It has been observed that at 900°C the aluminium hydroxide powders are transformed to n-AbOa, This n-alumina has market as activated alumina. Therefore, the invention has commercial importance to produce activated alumina. The process developed for the treatment of aluminium dross is unique in nature. The novelty of the present process is that q-alumina a high valued product can be produced from waste aluminium dross. So far the treatment options available mostly aimed to optimize the recovery of metal part from oxide part and rest was land filled. There are other options where oxide part is further heat treated to obtain oxides, which may be used as abrasive materials, ceramics or refractory use. The carbon present in the dross is removed as CO2 when treated at higher temperatures. Some other processes where sulphuric acid is used to treat dross produced impure aluminium sulphates because either it will be contaminated with iron hydroxide or most of the leachable alloying elements will ultimately end up with aluminium sulfate. The process developed for treatment of waste aluminium dross consists of various inventive steps such as washing of dross, leaching of original and washed dross, filtration of leached slurry to separate out aluminium sulfate solution and residue. Residue washing is performed to take out residual aluminium sulfate associated with leached residue. Precipitation of aluminium hydroxide is carried out from leached solution by aqueous ammonia. Iron is separated out earlier at pH around 3.8 to 4.0. Precipitation of aluminium hydroxide starts around pH 5 and continued up to around pH 7.0. This aluminium hydroxide is amorphous in nature containing around 58% water and sulfate ion. The activated alumina such as n-alumina has been prepared by dehydration and desulfurisation of this aluminium hydroxide at 900°C. The activity of n-alumina is determined by copper adsorption experiments. The acid leaching of dross is considered to be the main controlling factor for commercialization purpose. 15% acid at 10% solid (washed dross) concentration may be considered beneficial for process cost analysis because 6-8% extra recovery of alumina by increasing the acid concentration may not worth the cost of extra acid. The following examples are given by the way of illustration of the working of the invention in actual practice and therefore should not be construed to limit the scope of the present invention. Example -1 Table-2 shows the washing data of aluminium dross with dimineralised water at 80°C temperature. In the study 10g of dross is taken, water taken is 100mL, washing time is 2h. The Table-2 shows various species present in the original dross and in the dross after washing. Percentage of recovery of various water soluble elements is shown. It has been calculated that around 6.5% salt is taken out from the dross and around 0.5% salt is staying back in the solid. The x-ray diffraction data confirm the salt to be a mixture of NaCI and KCI. Example - 2 Evaporation of salt is carried out by taking the washed water obtained after repeated washing of dross containing salts of NaCI and KCI. The washed water is generated by repeated washing of aluminium dross with recycled wash water from previous washing step after filtration. The experiment started by taking 100mL of water. The wash liquor is sent to the next step of dross washing. Each time extra water is added to make up the wash solution to 100mL. The residue left in the filter paper is washed with 50mL of water each time. In the reported experiment 60g of dross is washed by taking 10g of dross each time. After 6th washing the wash water contains around 20gpl of salt of 100ml_ and the residue wash liquor contains around 6.7gpl of salt of 300ml. The evaporation was carried out in an open container to drive out water at boiling. The white mass of dual salt remained in the container, which was taken out and calculated for total recovery. Both the solutions are evaporated as above and total salt obtained is 3.9g. This value corresponds 6.5% of the dross and indicates around 0.5% salt is staying back with the dross. The x-ray diffraction data confirms the salts to be mixture of NaCI and KCI. Example - 3 Table-3 shows the percent recovery of alumina (A^Oa) when treated with sulfuric acid. Sulfuric acid concentration has been changed. The experiments are shown for original dross containing salts. Analysis of alumina is calculated by standard EDTA-ZnSC>4 method. The sulfuric acid solution is taken 100mL and temperature of operation is 95°C. It is observed that with increase in percentage of acid, alumina recovery increased up to 30% acid but above this concentration recovery is decreased. Around 88% recovery is obtained for 30% acid. The recovery remained almost same for 40% and 50% acid. The recovery has decreased to 77% when 70% acid is used. Example - 4 Table - 4A to 4C show the solids percentage at which maximum recovery is obtained. The amounts of acid taken are 25ml_, 30mL, and 40mL. In each experiment amount of dross taken is 10g. Solids percentage is varied by adding different amounts of water. The temperature of study is 95°C. Table-4A (25ml_ acid) It has been shown that 10% solids concentration is found to be the optimum for obtaining maximum recovery. Example - 5 Table-5 shows the kinetic study of dissolution of aluminium dross in 15%, 20% and 25% sulfuric acid solution. Experimental conditions: original dross taken-10g, 100ml_ solution, temperature- 95°C. Table-6 shows the percentage of alumina recovery obtained for the three different conditions dross such as original dross (with salts), washed dross and washed & dried dross. It has been found that washed dross showed maximum recovery than other two drosses. The maximum recovery obtained for all the three drosses is at 30% acid concentration. For washed dross recovery of 92% & 84% observed at 30% acid and 15% acid respectively. Experimental conditions: original dross taken -10g, dross concentration - 10%, concentration of acid varied between 15 to 50%, 100ml_ acid solution, temperature-95°C. Precipitation of aluminium hydroxide is carried out from aluminium sulfate solution obtained after dissolution of aluminium dross in sulfuric acid with 2.5% aqueous ammonia solution. The concentration of AI3+ is maintained -0.25M. the experiment started as follows; 50g washed dross + 500mL of 20% sulfuric acid solution, treated for 3h at 95°C. The leaching efficiency is 76% of alumina. The slurry is filtered and washed. Total filtrate including wash liquor is made 1000 ml. The concentration of AI2Os calculated is 24.73 g/L (0.485M). The solution is diluted to make the concentration of Al3* 0.25M with dimineralised water. The solution pH at this point is 1.1. The precipitation experiment started with the addition of 2.5% ammonia solution rapidly up to pH 3.5 and then it started adding slowly, at pH 3.8 to 4.0 brown iron hydroxide started precipitating out. At around pH 4.4 the solution with precipitated iron hydroxide is filtered. The clear filtrate again taken for further addition of ammonia, at around 5 pH aluminium hydroxide started precipitating out. The addition of ammonia continued till the pH reached 7. The slurry filtered and the solid mass (aluminium hydroxide) is dried overnight at 80°C. The precipitated aluminium hydroxide is weighed and found 46.92g. This hydroxide is heated in a muffle furnace at 900°C and found the weight of dehydrated material as 19.64g. The total moisture and sulfate is found to be 58.1% and AI2O3 is around 42%. This dehydrated material is identified as n,-alumina through X-ray powder diffraction phase analysis. This materiaf is a good activated alumina. Important features of the present invention: 1. The maximum salt recovered is 6.5% with single step washing. Similar result is obtained when multistage washing is used. 2. Washed dross is found to be the best material for alumina dissolution and one hour dissolution is found to be sufficient to obtain steady state value. 3. Aluminium dross of 10% concentration is the optimum concentration of solid loading. 4. Dissolution studies of aluminium dross showed 84% recovery of alumina at 15% H2SO4 concentration with 10% solid concentration, while recovery of 92% is obtained at 30% acid concentration for washed dross. 5. Amorphous aluminium hydroxide is obtained by neutralizing aluminium sulfate solution with ammonia. This hydroxide is a good precursor material for preparation of various dehydrated aluminas. 6. n-alumina is obtained by heat treatment of amorphous hydroxide at 900°C. This is a very good activated alumina. Advantages 1. Utilisation of waste aluminium dross for production of high valued product, which is other wise in most of the cases stock piled. 2. Avoiding pollution of adjoining area 3. Waste minimization by recycling the aluminium dross 4. The process has potential for commercialization. We claim 1. A process for producing high valued -alumina from aluminium dross, containing alumina and alloying elements and comprising water soluble salts, has been developed under atmospheric pressure condition, which comprises the steps of (a) washing of aluminium dross with wash water to remove water soluble salts, (b) evaporation of the wash water to crystallise out KCI and NaCI, (c) dissolution with H2SO4 at a temperature 95°C to solubilise alumina to form aluminium sulfate aqueous solution, (d) precipitation of aluminium hydroxide from the aluminium sulfate solution with 10% aqueous ammonia solution, e) heating the aluminium hydroxide to get r|-alumina and f) copper adsorption for -Al2O3 to find its adsorption capacity. 2. The process as claimed in 1, wherein the washing of aluminium dross is carried out at 80°C. 3. The process as claimed in 1-2, wherein 6.5% salt is recovered from aluminium dross when treated with water. 4. The process as claimed in 1, wherein the H2SO4 dissolution is carried out with aluminium dross containing salts show an optimum AI2O3 recovery of 88% at 30% acid concentration and at 10% aluminium dross concentration. 5. The process as claimed in 1 & 4, wherein the H2SO4 dissolution is carried out with washed aluminium dross show AI2O3 recovery of 92% at 30% acid concentration and at 10% aluminium dross concentration. 6. The process as claimed in 1, 4-5, wherein the H2SO4 dissolution is carried out with washed & dried aluminium dross show AI2O3 recovery of 91% at 30% acid concentration and at 10% aluminium dross concentration. 7. The process as claimed in 1, 4-6, wherein the maximum recovery obtained at 50% H2SO4 concentration is 94%. 8. The process as claimed in 1, 4-7, wherein the maximum recovery obtained at 15% H2SO4 concentration is 84% for washed dross. 9. The process as claimed in 1, 4-8, wherein the optimized time for dissolution is found to be 1h. 10. The process as claimed in 1, wherein the aluminium sulfate solution produced in H2SO4 treatment is further treated with dilute ammonia (2.5 % by volume) by adding drop wise (5mL/min) the ammonia solution to aluminium sulfate solution to precipitate aluminium hydroxide. The concentration of Al3+ is kept 0.25M. The iron hydroxide precipitated is separated at 4.4 pH. The filtrate is further taken for precipitating aluminium hydroxide by increasing the pH up to 7. The aluminium hydroxide is separated by filtration and dried at 80°C for overnight. 11. The process as claimed in 1 & 10, wherein the aluminium hydroxide Precipitation is carried out at room temperature only. 12. The process as claimed in 1 & 10-11, wherein the aluminium hydroxide produced is heat treated at 900°C to obtain -alumina. 13. The process as claimed in 1& 10-12, wherein the activity of -alumina is established with adsorption of copper. 14. A process for production of -alumina from waste aluminium dross by sulfuric acid dissolution method substantially as herein described with reference to the examples.

Documents:

398-DEL-2006-Abstract-(14-02-2012).pdf

398-del-2006-abstract.pdf

398-DEL-2006-Claims-(14-02-2012).pdf

398-del-2006-claims.pdf

398-DEL-2006-Correspondence Others-(14-02-2012).pdf

398-del-2006-correspondence-others 1.pdf

398-del-2006-correspondence-others.pdf

398-DEL-2006-Description (Complete)-(14-02-2012).pdf

398-del-2006-description (complete).pdf

398-del-2006-form-1.pdf

398-del-2006-form-18.pdf

398-del-2006-form-2.pdf

398-del-2006-form-3.pdf

398-del-2006-form-5.pdf