Title of Invention

A COMPOSITION FOR PREPARING NON- HAZARDOUS BUILDING BLOCKS AND PROCESS FOR PREPARATION THEREOF

Abstract

A composition for preparing non-hazardous building blocks and process for preparation thereof During the metallic zinc extraction in hydrometallurgical process, huge quantity of waste as jarosite is released in zinc industry which contain significant concentration of zinc, lead, cadmium manganese, sulphur and other trace elements, which are far above than that of normal soil. There is a release of toxic element in soluble form from hazardous jarosite and which ultimately contaminates the soil, ground water and aquatic life. The present invention is useful for recycling hazardous jarosite through detoxification/ immobilization using non hazardous wastes such as coal combustion residues (CCRs) / marble processing wastes as well as converting it in to environmental friendly blocks for utilization in construction purposes.

Full Text

Field of the invention: The present invention relates to a composition for preparing non-hazardous building blocks and process for preparation thereof. The present invention is useful for recycling hazardous jarosite through detoxification/ immobilization using non hazardous wastes such as coal combustion residues (CCRs) / marble processing wastes as well as converting it in to environmental friendly blocks for utilization in construction purpose. Background and prior art of the invention: Universally, Zinc industries are realizing huge quantity of jarosite during zinc metal extraction process as solid residues and due to the presence of toxic substances like lead, zinc, cadmium etc., jarosite is categorized as hazardous waste and becomes major environmental concern. The present invention is useful in immobilizing the hazardous jarosite for safe land disposal as well as significantly contributes for value addition in developing non-hazardous, environmental friendly building blocks with incorporation of clay, CCRs/ marble processing wastes. Blocks developed from hazardous jarosite can be used in variety of application in construction sector. The density of the blocks varied from 1.64 to 1.74kg/cm2 with compressive strength of 45.5 kg/cm2 to 140 kg/cm2. The water absorption capacity of jarosite blocks varies from 14.5-18.2 % and has low shrinkage (3.5-12%) and confirming the better quality recommended in (>35kg/cm2) Indian standard specification (IS 2248:1992) for its use in construction sector. The US EPA approved toxicity characteristics leachate studies revealed that the leachate of toxic elements (Pb, Cd, Ni, As, Se, S, Cr, etc.,) in the blocks are below the values recommended by USEPA toxic limits and can be used in an environmental friendly application. Fired clay blocks are commonly used as one of the building components in the construction sector. To substantiate the depletion of existing natural resources like clay, silt, sand and fine aggregates in manufacturing blocks, the present invention provide partial solution to find an alternative for the conventionally used blocks. Also this will find a socio, techno-economic solution to safe guard the clean and green environment by effectively utilizing non-hazardous industrial wastes in safely recycling hazardous jarosite. World wide huge quantities of hazardous wastes are generated during different industrial processes and development of newer products. As reported by Hsing et al., 2004, with effect from 1992 the treaty of the Basel Convention governs the transboundary movement of hazardous waste and more than 148 countries and the European Community have ratified the recommendation to minimize unfavorable environmental consequences of improper management of hazardous wastes. Safe management of such huge quantity of hazardous wastes is now a global concern to achieve the objective of environmental sound management of Basel Convention and has been reported by several researchers like Alter (2000); Harvey, 2000; Saxena and Jotshi, (1996) etc., In India, ~ 4.5 million tonnes of hazardous wastes is being released annually during different industrial process and product development. According to the data of MOEF Web site (2004), work done by Asolekar (2003) and Asokan et al. (2003), it is imperative that out of 4.5 million tones, -1.7 million tonnes waste is recyclable; 1.89 million tonnes is incinerable; and -2.5 million tonnes is disposable in secured land fill. In hydrometallurgical process of metallic zinc extraction from zinc sulphide or sulphide ore, huge quantity of waste is being released universally as solid residues. Bhat et al. (1987), Singh (1996), Ismael and Carvalho (2003) explained that metallic zinc extraction process is mainly of (a) goethite process (FeOOH), (b) jarosite process (XFea (SO4)2(OH6) and Hematite process and each process has its own advantages and disadvantages. Further, literature review showed that in jarosite process, an Fe (3+) compound of the type X [Fe3(SO4)2(OH)6] is precipitated by adding alkali metal or ammonium ions and the formation of jarosite and its equilibrium condition is as follows (Mymrin & Vanamonde (1999), Hage and Schuiling (2000) and Montanaro et al. (2001): 3 Fe2(SO4)3+ X2 SO4 +12 H2O 2X Fe3 (SO4)2 (OH)6+6H2SO4 where X represents H3O+, Na+, K+ NH4 +, Ag+, Li, or 1/2 Pb 2+ Earlier work done by Leclerc et al. (2003) and Asokan (2003) showed that huge quantity of Jarosite waste released as residues / mud during the hydrometallurgical zinc extraction process are universally categorized as hazardous waste due to the presence of toxic substances like Zn, Pb, Cd, S, Fe etc.,.Mostly these wastes are stored in different types of closed containers or sealed reservoirs in the premises of production unit. The work carried out by Alfantazi and Dreisinger (2003) revealed that the solid residues produced during this metal extraction process involves major environmental and ecological problem due to the presence of toxic species like lead, cadmium and zinc etc., and their safe management become major challenge for the waste generators. Arslan and Arslan (2003) reported that the major quantity of Jarosite is generated mainly from China, USA, Spain, Holland, Canada, France, Australia, Yugoslavia, Korea, Mexico, Norway, Finland, Germany, Argentina, Belgium and Japan. In India, Hindustan Zinc Limited (HZL) has a multi-unit of mining and smelting installed capacities of 3.49 million tonnes / per year. Zinc is manufactured from four smelters located in the states of Rajasthan, Andhra Pradesh, Bihar and Orissa. Debari Zinc Smelter, Udaipur and Chanderiya Lead Zinc Smelter, Chittorgarh (Rajathan) and Zinc Smelter (Vishakhapatnam ) are the major industries generates Jarosite in India. Singh, (1996), Raghavan and Upadhyay (1999) and Hindustan Zinc Limited web site, August (2003) reported that during Zinc metal extraction process, Dabari zinc smelter produces ~ 49,000 tonnes per annum (tpa) of zinc metal and as a consequence huge quantity of wastes/ zinc smelter residues namely Jarosite is being released as hazardous waste. Few techniques have been developed worldwide for remediation of hazardous wastes containing priority toxic elements. Lehman (1982) and Barna et al. (1997) impart solidification /stabilization (s/s) process is one of the techniques, now, commonly used to inhibit the transport of heavy pollutant elements in to the surrounding environment and offers improvement in the physical characteristics that reduce the leach-ability of toxic metals. However, Romero and Rincon (1997) explored the possibility to recover valuable elements/value added material and to transform them into other forms less harmful to the environment. Work carried out by Gupta (1988) and Acharya et al. (1992) showed that the ground water is contaminated due to the disposal of jarosite. Mostly, these wastes have been stored in the premises of the smelter plant and yet no work has been done on recycling and utilization of hazardous jarosite. Jarosite is hazardous due to the presence of these toxic substances. Disposal of jarosite is now becoming expensive because of increasingly stringent environmental protection regulations and presently this jarosite is stored in different types of closed containers or sealed reservoirs in the premises of production unit. However, during marble cutting, polishing, processing, grinding activities about 4.5 million tones of marble waste as a residues are being released in India, which is an environmental concern. Further, in India, coal based thermal power plants are annually releasing ~112 million metric tonnes of coal combustion residues (CCRs). Environmental pollution due to the release of such huge quantity of these wastes all over the world are cited to be one of the major source of pollution affecting the general aesthetics of environment in terms of land use, health hazardous, air, soil and water in particular and thus leads to environmental dangers. Hence, safe disposal, gainful recycling and utilization of these wastes are having great practical importance for socio- techno -economic development. This invention provides a solution for effectively utilizing hazardous jarosite with CCRs or marble processing wastes in developing better quality light weight building blocks and meeting the quality standards. The studies carried out by Mymrin and Vaamonde (1999), Hage and Schuiling (2000) showed that there is a treatment process for the disposal of jarosite wastes and has potentials for use in tiles, ceramic products. But, no experimental results are reported. Not much work has been carried out yet on safe management of hazardous Jarosite. But, no work has been reported world wide on gainful utilization of hazardous jarosite in developing environmental friendly lightweight building blocks. Objects of the invention: The main objective of the present invention is to immobilize toxic substances in hazardous jarosite and effective recycling and utilizing them as raw materials in developing value added materials to achieve the objective of Environmentally Sound Management of Basel Convention. Another object of the present invention is the utilisation of other industrial wastes such as OCRs and marble waste, which are causing major environmental pollution, as an additive to immobilise hazardous substance in jarosite and to obtain values added products. Still another object of the present invention is to find an alternative for the conventionally manufactured fired clay blocks being presently used as one of the major building components. Yet another object of the present invention is to develop lightweight blocks by saving of clay, soil and other natural resources used in developing building materials. Summary of the invention: During the metallic zinc extraction in hydrometallurgical process, huge quantity of waste as jarosite, is released in zinc industry, which contains significant concentration of zinc, lead, cadmium manganese, sulphur and other trace elements, which are far above than that of normal soil. There is a release of toxic elements in soluble form from hazardous jarosite and which ultimately contaminates soil, ground water and aquatic life. According to Indian and International Environmental regulatory framework, jarosite is categorized as hazardous waste and is major environmental concern due to the presence of toxic substances and poses serious problems for its disposal and storage. The results of the present invention revealed that jarosite is silty clay loam in texture having ~ 63.5% silt sized and -32.5% clay sized particles. Almost 90% of the jarosite particles are - 16 urn in size. The morphological study showed that jarosite is smooth and non-uniform in structure and shape. The major mineral phase of jarosite is Potassium Iron Sulphate Hydroxide {KFes (S04)2(OH)6J and Iron Sulphate Hydrate {2Fe203SOs-5H2O}. The high electrical conductivity in jarosite (-13.5 dS/m) indicates that the presence of cations and anions are predominant over other additives. The major portion of jarosite consists of iron (~23.5%), sulphur (~12.0 %) and zinc (~8.0 %). The other constituents such as calcium, aluminium, silicon, copper, cadmium, lead, and manganese are also present in the range of 0.5 to 5%. Statistically designed experimental trials revealed that the compressive strength of jarosite blocks ranges from 45.5 kg/cm2 to 140kg/cm2 and the water absorption capacity varies from 14.51-18.26 % and shrinkage varied from 3.5-12%. This has confirmed the quality requirement (35kg/cm2) as per the Indian standard specification (IS 2248:1992) for its use in construction sector. Further, the USEPA approved toxicity characteristics leachate studies revealed and confirmed that the leachate of toxic elements (Pb, Cd, Ni, As, Se, S, Cr, etc.) in the blocks are below the values recommended by USEPA toxic limits and can be used in environmental friendly applications. Accordingly, the present invention provides a composition for preparing non-hazardous building blocks comprising (a)hazardous jarosite waste released during the metallic zinc extraction in hydrometallurgical process, (b) structural materials along with (c) binder and/or additives, wherein the ratio of component (a) to (b) is in the range of 1:1 to 1:4 and the component (c) is 1 to 40% [wt/wt] of the mixture of (a) and (b). The invention further provides a process for recycling and gainfully utilizing hazardous jarosite in preparing non-hazardous building blocks, wherein the process steps comprises: i. mixing together (a) hazardous jarosite waste along with (b) structural materials and (c) binders/additives to obtain a composite matrix, wherein the ratio of component (a) to (b) is in the range of 1:1 to 1:4 and the component (c) is 1 to 40% [wt/wt] of the mixture of (a) and (b); ii. kneading the composite matrix as obtained in step (i) using water to bring it to a homogeneous workable state; iii. moulding the kneaded matrix as obtained in step (ii); iv. allowing the moulded matrix as obtained in step (iii) to dry; v. firing the dried matrix as obtained in step (iv) at 850 to 950 degree C for 90 to 110 minutes to obtain non-hazardous building blocks; vi. testing the quality of the blocks as obtained in step [v] in terms of density, shrinkage, water absorption capacity, efflorescence and compressive strength. Detailed description of the invention: The hazardous Jarosite released from hydrometallurgical process of metallic zinc extraction is complex and its quality and quantity make the task more complex for safe disposal. Similarly, huge quantity of CCR and marble cutting and processing wastes being released as solid wastes in India. Apart from water contamination, already accumulated wastes and their increasing annual production are becoming major source of pollution for surrounding environment including soil, vegetation, and aquatic life and hence, its disposal leads to major environmental threats. The present invention provides a multidisciplinary solution for conversion of hazardous jarosite in to non-hazardous material using CCRs and marble processing wastes. So far no work has been carried out / reported on recycling and gainful utilisation of hazardous jarosite in developing environmental friendly building blocks. Very little work has been cited on the treatment process for the disposal of these wastes. Work carried out by Mymrin and Vaamonde (1999), Hage and Schuiling (2000) so far focused primarily on the recovery of zinc from the process wastes, leaching of toxic metals, stabilization/ solidification of hazardous wastes. Traditionally fired clay blocks are being used as one of the major and important building material in the constriction sector. To meet the demand of these blocks, indiscriminate exploitation of natural clay leads in damaging the environment and inherent natural resource. In order to safeguard the environment and to meet the scarcity of blocks in the construction industries, there is an urgent need to find an alternative to replace these conventional building blocks. Huge quantities of so-called hazardous and non-hazardous industrial wastes are considered to be secondary resources, which can be recycled and used gainfully through an innovative area of research to develop alternative materials / technologies in an economically viable and socially acceptable manner. In the present invention, several experiments were conducted to develop quality blocks using jarosite and with various additives. Result revealed from the statistically designed experiments that low-density blocks (1.5 - 1.7 gm /cm3) could be developed from jarosite having compressive strength ranges from 45.5 kg/cm2 to 140kg/cm2. Water absorption capacity of jarosite blocks varied from 14.51-18.26 % and shrinkage varied from 3.5-12%. This is also confirming the quality as per the Indian standard specification (IS 2248:1992) for its use in construction sector. Further, toxicity characteristics leachate studies revealed that the leachate of toxic elements in the blocks is below the concentration/ toxic limits recommended by USEPA for its use in an environmental friendly application Novelty: The novelty of the present invention is recycling, value addition and gainful utilisation of hazardous jarosite in developing environmental friendly and lightweight building blocks. The following examples are given by 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 The invention was done at Regional Research Laboratory (CSIR) Bhopal. In each case standard methods were followed for sample processing and characterization in terms of physical, chemical, mineralogical and morphological and engineering properties. In the first set of experiments, hazardous Jarosite waste was mixed together with clay in the ratios of 1:1, 1:2, 1:3 and 1:4. To reduce the plasticity of clay for obtaining good workability 5, 10, 15, 20 and 25% sand was added on each clay jarosite matrixes/ materials separately. Using high purity water the composite matrix was kneaded well till it becomes a homogeneous workable state. The tempered matrix was then used for moulding. The well-prepared jarosite matrix was moulded in rectangular cast iron mould (7.5 cm x 3.5 cm x 3.5 cm) by hand press. The casted bricks were then removed from the moulds and allowed to air dry. After air-drying the bricks were placed in the Muffle furnace and fired at 850-950° C for 90 to 110 minuets during which the composites matrix become densified and hardened. The quality of the bricks interms of density, shrinkage, water absorption capacity, efflorescence and compressive strength were tested for the fired bricks following IS 3495 (Part 1&2): 1992. Toxicity Leachate Characteristics of heavy metals and toxic element in Jarosite composits bricks were studies following US EPA approved and developed Toxicity Leachate Characteristics Procedure (TCLP) using Zero Head Space Extractor, Millipore, USA. Total heavy metals and toxic elements such as Cu, Zn, Mn, As, Se, Cr, Ni, Co, Cd, Pb, Ag, etc., were analysed for the TCLP extract by Graphite unit of Atomic Absorption Spectrophotometer (AAS), Z-5000, Hitachi, Japan (Jackson, 1973). For all cases high purity water from Elgastat Prima and Maxima system England was used. The mineralogical content in the raw materials and changes in jarosite composite bricks was done by X-Ray Diffractometer- PW-1710 Philips, Motherland with Quasar software packages. The microstructure characteristics of jarosite was analysed by Scanning Electron Micros scope- Model JOEL JSM-5600, Japan with Energy Depressives X-ray Spectroscopy (EDS) analysis facilities, using the software of Oxford Model link Pendafet- 1C 300. EXAMPLE-2 Jarosite wastes were mixed with Coal Combustion Residues (CCRs) at the ratios of 1:1, 1:2, 1:3 and 1:4. Calcium sulphate (CaSO4) was used as binder and additives at the concentration of 5, 10, 15, 20 and 25% along with the jarosite CCRs composites. The well-kneaded matrix was moulded in a rectangular cast iron mould at a pressure about 20kg/ cm2. The casted products/ bricks were then removed from the moulds and allowed to air dry and then fired at 850-950° C for 90 to 110 minuets. The quality of the fired densified bricks was evaluated in terms of density, shrinkage, water absorption capacity, florescence and compressive strength as per IS 3495 (Part 1&2): 1992. Toxicity Leachate Characteristics of heavy metals and toxic element in Jarosite composits bricks were studies following US EPA approved and developed Toxicity Leachate Characteristics Procedure (TCLP) using Zero Head Space Extractor, Millipore, USA. Total heavy metals and toxic elements such as Cu, Zn, Mn, As, Se, Cr, Ni, Co, Cd, Pb, Ag, etc., were analysed for the TCLP extract by Flame and Graphite unit of Atomic Absorption Spectrophotometer (AAS), Z-5000, Hitachi, Japan. For all cases high purity water from Elgastat Prima and Maxima system England was used. The mineralogical changes in jarosite composite bricks were done by X-Ray Diffractometer-PW-1710 Philips, Motherland with Quasar software packages. EXAMPLE-3 Jarosite wastes along with clay were mixed together at the ratios of 1:1, 1:2. 1:3 and 1:4. As an additive, Coal combustion residues at the concentration of 10, 20, 30 and 40% was used to stabilize jarosite matrix. The composite matrix was kneaded well till it becomes a homogeneous workable state and other procedure followed in example 2 was followed. As per the IS 3495 (Part 1&2): 1992 standard bricks were tested for its density, shrinkage, water absorption capacity, florescence and compressive strength for confirming its quality for construction application. Further, toxicity leachate Characteristics, chemical, mineralogical and morphological properties were studied as in case of example 2, Jarosite wastes were mixed with clay at the ratios of 1:1, 1:2, 1:3 and 1:4. Marble dust was used as an additive at the concentration of 1 - 30 % at the incremental level of 5% along with the jarosite clay composites. At a pressure 0 to 20kg/ cm2 well-kneaded matrix was casted and then removed from the moulds. After oven dry at ~ 35° C these bricks were fired at different temperature from 850-950° C for 90 to 110 minutes. The densified and hardened bricks were tested for their quality as per IS 3495 (Part 1&2): 1992 and US EPA approved and developed Toxicity Leachate Characteristics Procedure (TCLP). Total heavy metals and toxic elements such as Cu, Zn, Mn, As, Se, Cr, Ni, Co, Cd, Pb, Ag, etc., were analysed for the TCLP extract using Atomic Absorption Spectrophotometer (AAS), Z-5000, Hitachi, Japan and confirmed the quality standard. The results revealed from the above example/ studies that during sintering process under solid-state reaction, the toxic substances/elements in jarosite were detoxified/immobilised through complexing in the silicate matrix. Result revealed that the present invention that jarosite bricks are low in density (1.5 -1.7 gm /cm3) as compared to the conventionally available fired clay bricks as well as cement based bricks. Compressive strength reached from 45.5 kg/cm2 to 140kg/cm2 with water absorption capacity of 14.5-18.3 % and shrinkage 3.5 -12%. As per the Indian standard specification (IS 2248:1992) jarosite based bricks are meeting the quality. And the toxic elements leachate behaviour in the jarosite bricks is below the concentration/ toxic limits recommended by USEPA. Admixing of Jarosite clay ratio at 1:2 and 1:3 with 15% as well as 30 % either with CCRs or with marble dust showed optimum results for utilization in construction sector in an environment friendly application. This shows that there is a great potential for recycling and gainfully utilizing jarosite and converting it into non-hazardous building bricks using CCRs and Marble dust. Advantages: The main advantages of the present invention are: 1. Converting hazardous jarosite in to non hazardous materials 2. Development of alternative and lightweight building blocks for the substitute to the existing fired clay blocks 3. Utilisation of other industrial wastes such as CCRs and Marble waste, which are causing major environmental pollution, as an additive to obtain values added products 4. Saving of clay soil and other natural resources in developing building materials 5. Protection of environmental quality / maintaining the clean and green environment and comply with the Basel Convention Environmental Sound Management. We claim: 1. A composition for preparing non-hazardous building blocks comprising (a)hazardous jarosite waste released during the metallic zinc extraction in hydrometallurgical process, (b) structural materials along with (c) binder and/or additives, wherein the ratio of component (a) to (b) is in the range of 1:1 to 1:4 and the component (c) is 1 to 40% [wt/wt] of the mixture of (a) and (b). 2. A composition as claimed in claim 1, wherein the structural materials are preferably selected from the group comprising of sand, clay, CaSO4, coal combustion residue [CCR] and marble dust. 3. A composition as claimed in claim 1, wherein the structural material is preferably sand used at a concentration of 5 to 25%. 4. A composition as claimed in claim 1, wherein the structural material is preferably CaSC>4 used at a concentration of 5 to 25%. 5. A composition as claimed in claim 1, wherein the structural material is preferably coal combustion residue used at a concentration of 10 to 40%. 6. A composition as claimed in claim 1, wherein the structural material is preferably marble dust used at a concentration of 1 to 30%. 7. A process for recycling and gainfully utilizing hazardous jarosite in preparing non- hazardous building blocks, wherein the process steps comprises: i. mixing together (a) hazardous jarosite waste along with (b) structural materials and (c) binders/additives to obtain a composite matrix, wherein the ratio of component (a) to (b) is in the range of 1:1 to 1:4 and the component (c) is 1 to 40% [wt/wt] of the mixture of (a) and (b); ii. kneading the composite matrix as obtained in step (i) using water to bring it to a homogeneous workable state; iii. moulding the kneaded matrix as obtained in step (ii); iv. allowing the moulded matrix as obtained in step (iii) to dry; v. firing the dried matrix as obtained in step (iv) at 850 to 950 degree C for 90 to 110 minutes to obtain non-hazardous building blocks; vi. testing the quality of the blocks as obtained in step [v] in terms of density, shrinkage, water absorption capacity, efflorescence and compressive strength. 8. A process as claimed in claim 7, wherein the structural materials are preferably selected from the group comprising of sand, clay, CaSO4, coal combustion residue [CCR] and marble dust. 9. A process as claimed in claim 7, wherein the structural material is preferably sand used at a concentration of 5 to 25%. 10. A process as claimed in claim 7, wherein the structural material is preferably CaSO4 used at a concentration of 5 to 25%. 11. A process as claimed in claim 7, wherein the structural material is preferably coal combustion residue used at a concentration of 10 to 40%. 12. A process as claimed in claim 7, wherein the structural material is preferably marble dust used at a concentration of 1 to 30%. 13. A process as claimed in claim 7, wherein the water used to knead the matrix is high purity water. 14. A process as claimed in claim 7, wherein firing of the moulded matrix is carried out in a muffle furnace. 15. A process as claimed in claim 7, wherein the kneaded matrix is preferably moulded in rectangular cast iron mould (7.5 cm x 3.5 cm x 3.5 cm) by hand press. 16. A process as claimed in claim 7, wherein the building blocks are preferably bricks. 17. A composition for preparing non-hazardous building blocks and process for preparation thereof substantially as herein described with reference to the examples.

Documents:

737-del-2006-Abstract-(12-12-2013).pdf

737-del-2006-abstract.pdf

737-del-2006-Claims-(12-12-2013).pdf

737-del-2006-claims.pdf

737-del-2006-Correspondence Others-(12-12-2013).pdf

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

737-del-2006-correspondence-others.pdf

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

737-del-2006-description (provisional).pdf

737-del-2006-form-1.pdf

737-del-2006-form-18.pdf

737-del-2006-form-2.pdf

737-del-2006-Form-3-(12-12-2013).pdf

737-del-2006-form-3.pdf

737-del-2006-form-5.pdf