PROCESS FOR COMPLETE CONVERSION OF MULTIPLE INDUSTRIAL WASTES TO SUSTAINABLE ALTERNATIVES AND USABLE PRODUCTS

Abstract

The invention is directed towards a process for complete conversion of multiple industrial wastes to sustainable alternatives and usable products resulting in water in-soluble product alike chemical gypsum useful for cement manufacturing used in construction industry. The inventor has utilized industrial wastes from multiple industries together taking into consideration their chemical and physical properties without using any form of energy. The whole process is carried out at ambient temperature under open sky. In described two exemplary processes, the inventor has disclosed process comprising the steps of mechanically mixing metallurgical inert waste of aged dry Jarofix containing crystallized Gypsum with freshly generated Jarosite or dry/wet Red Mud followed by addition of adequate acidic concentration waste water, calcitic wastes, pozzolanic property enhancers & lime treatment. The multiple wastes mix crystallized chemical gypsum mass on drying is used as a whole without any leftover.

Claims

1. A process of complete conversion of multiple industrial wastes to sustainable alternative usable products wherein the same comprises the steps of: (a) Mechanically mixing various industrial solid dry & wet wastes including effluent/spent acidic water and excessive Jarosite or Red Mud moisture, based on their compatible physical and chemical properties, drying under open sky—rain & dew protected through Tarpulin covering; (b) Activating the dead and inert wastes like marble dust & Jarofix, cement kiln dust or any other such suitable wastes, towards seeding effect or for their full reuse; (c) Catalysing the reaction through addition of another landfilled non-usable waste; (d) Mixing compatible wastes towards producing pozzolanic properties material;

2. A process of complete conversion of multiple industrial wastes to sustainable alternative usable products wherein the same comprises the steps of: Mechanically mixing metallurgical waste in the form of aged dry Jarofix before or after lime treatment, containing crystallized Gypsum with freshly generated Jarosite in a proportion of 0.25 to 0.5:1 by weight or by full use of either Jarofix or Jarosite, or use of Red Mud alone; Addition of fresh or preferably spent H.sub.2SO.sub.4 generated as acidic waste in chemical industries duly filtered in a ratio of 0 to 30% by weight. Addition of fresh water or preferably effluent acidic waste water generated internally in different industry after filtering of suspended particles or foreign matters, free of toxic gases in the ratio of 0 to 30% by weight. Addition of marble cutting dust or cement kiln dust & limestone sieve cutting tailing in ratio of 0 to 50% by weight; Addition of MEE salt waste generated in zinc industry, carrying constituents of sodium, sulphate and chlorine in a ratio of 0 to 15% by weight; Addition of quarry dust waste in a ratio of 0 to 25% by weight; Addition of lime slurry in a ratio of 0 to 15% by weight.

3. A process of complete conversion of multiple industrial wastes to sustainable alternative usable products as claimed in claim 1 wherein mixing of the acidic and alkaline wastes and other additives is carried out in a stationary or transit concrete rotary drum mixer operating continuously or intermittently, the mixed mass thereafter allowed to dry/cure for 24 to 48 hours under open sky, occasionally agitating the mass to restrict hardening.

4. A process of complete conversion of multiple industrial wastes to sustainable alternative usable products as claimed in claim 1 wherein mixing of the acidic and alkaline wastes and other additives is carried out in a stationary mixer or pug mill, operating continuously or intermittently the mixed mass dried thereafter by heating using any means, resulting in a low purity gypsum product.

5. A process of complete conversion of multiple industrial wastes to sustainable alternative products as claimed in claim 1 wherein the resulting product is water insoluble, non-pollutant, non-hazardous, fully usable possessing pozzolanic properties.

6. A process of complete conversion of multiple industrial wastes like Jarosite, Jarofix or Red Mud to sustainable alternative usable products like chemical gypsum of low purity used in cement manufacturing as claimed in claim 4 wherein the resulting product may not become completely water-insoluble, non-pollutant, non-hazardous or possess pozzolanic properties.

7. A process of complete conversion of multiple industrial wastes to sustainable alternative products as claimed in claim 1 wherein the industrial wastes are completely converted into usable sustainable alternative and no residual waste is left.

8. A process of complete conversion of multiple industrial wastes to sustainable alternative usable products as claimed in claim 1 wherein the resulting product is water-insoluble, non-pollutant, non-hazardous chemical gypsum fully usable possessing pozzolanic properties substantially as herein described and illustrated with reference to text descriptions made therewith.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0042] In the past, various attempts to solidify waste were and are being carried out using Portland cement but the resulting product is very permeable, porous, subject to leaching and deficient in mechanical strength. For promoting the interaction of various compounds, use of the other pozzolanic materials such as fly ash having better physical properties, was also tried but is rendered ineffective due to un-desirable quick setting of such materials even before the waste could be uniformly dispersed. Adding a small quantity of polymer cannot produce requisite strength in the resulting product and to achieve the needed strength, large quantities of the polymer are required. This again causes the problem of large volume handling & economy of scale.

[0043] Furthermore, the use of polymeric compounds to promote the Stabilization/Solidification (S/S) process effect is also undesirable because many polymeric compounds themselves are complex and hazardous making the resulting product toxic. In such case, chemical attack such as sulphate attack is catalyzed. Also, the resultant product degenerates over time. Thus, such disposal is undesirable.

[0044] The inventor studied various processes disclosed by scientists in last 40 years within US EPA regulatory framework on S/S process for mixed wastes.

[0045] Immobilizing of Jarosite waste generated by zinc industry is presently being done by said S/S method through treatment with admixture of lime and cement powder that exhibits low leachability & low compressive strength. The hazardous character of Jarosite waste is transformed into non-hazardous, chemically inert, physically stable mass called Jarofix that eliminates all short and long term environmental risks during and after its landfill.

[0046] During this process, cement partially decomposes around ⅓.sup.rd of Na-jarosite to evolve Ca-Jarosite, Ferric hydroxide and Sodium sulphate that further reacts with lime to crystallize gypsum, increasing pH and retaining minor amount of Ca—Al—Fe-silicate-sulphate-hydrate phases with traces of calcite.

[0047] Acid water in wet jarosite is neutralized using lime thereby precipitating heavy metals that get immobilised due to formation of respective insoluble carbonates and hydroxides.

[0048] Cured and aged Jarofix after years of aging & continued evaporation becomes moisture free & dry and can exhibit the same micro texture as those of freshly cured Jarosite. However the stored Jarofix gets depleted in Ca-Jarosite and cement phases and is enriched in gypsum and calcite that reflect high alkaline environment of Jarofix products. The said aged products also have increased amounts of Ca—Al—Fe-silicate-sulphate-hydrate phases possessing elevated Zn—Mg contents. This implies a further immobilization of residual water soluble Zn and Mg during storage making it entirely metal free.

[0049] (Ref: Lead-Zinc 2000 edited by John E Dutrizac, J. Gonzalez, J Henke, S. James, A Siegmund.)

[0050] The inventor in consideration of above finding, has invented a unique and novel process of converting industrial waste to sustainable alternatives.

[0051] The present invention discloses method of selecting wastes based on their chemical and physical properties and then mechanically mixing different types of wastes, followed by neutralizing the pasty mass to a neutral pH through addition of another calcite waste &/or small lime quantity for dolomite wastes, providing leeway for material in consistencies of different wastes mixed.

[0052] One such example of the present invention is producing crystallized chemical gypsum mass possessing pozzolanic properties by utilizing aged dry Jarofix containing crystallized Gypsum with freshly generated Jarosite.

[0053] Another example of the present invention is producing crystallized chemical gypsum mass possessing pozzolanic properties by utilizing aged dry or wet alkaline Red Mud.

[0054] The inventor after a careful thought, came to a conclusion that if aged Jarofix exhibits the same micro-texture as that of Jarosite and contains crystallized gypsum within its structure, it can also be used as a gypsum seeding agent when partially mixed with freshly generated Jarosite to optimise the gypsum percentage in total mix mass of wastes.

[0055] In carrying out the above Jarosite/Jarofix mix gypsum crystallization experiment, addition of around 10% low concentration acidic water is required. Use of acidic water from zinc secondary leaching process available in wet Jarosite could not solve the problem as it contained low concentration about 10 to 15 gms/ltr. Of H.sub.2SO.sub.4. The wetting of dry Jarofix and other mixed wastes mass required further addition of fresh water which is a scarce and costly resource.

[0056] Zinc industry treats effluent acidic water after gas cleaning by recycling through lime treatment which is a not a cost effective way. This acidic effluent waste water is added in place of fresh water but after increasing its acidic concentration to around 10% H.sub.2SO.sub.4 conc. To do so, the inventor utilized spent Sulphuric acid by way of adding one more waste to effluent acidic waste water after filtering the suspended foreign matters and venting toxic gases if any.

[0057] To optimise the gypsum crystallization in above described process a catalysing agent such as Sodium sulphate was essential. Since the cost of fresh sodium sulphate is prohibitive, using sodium sulphate waste was the alternative.

[0058] Zinc industry generates waste MEE salt, landfilled presently, which carries constituents of Sodium, Sulphate and Chlorine was used as catalyst after several experiments to overcome chlorine effect. Thus one more waste of Zinc industry got included in this novel sustainable initiative of multiple wastes conversion to usable product.

[0059] The use of Jarofix above was in low quantity whereas its landfill over last many years was in millions of tons world over. Exclusive Use of Jarofix towards required level of gypsum crystallization was therefore the necessity, however its low compressive strength makes it non-usable in cement manufacturing. Therefore additives that enhanced the physical properties of exclusive Jarofix wastes mixed mass was essential.

[0060] Towards imparting pozzolanic properties to the final chemical gypsum mass using multiple wastes, it could be achieved taking advantage of Ca—Al—Fe phases present both in Jarosite and Jarofix but Silica was missing in this composition. The inventor taking note of acidic chemical reaction in gypsum crystallization, thought of replenishing silica in the mixed mass by putting to use one more silica based waste. One such waste is from stone crushing named quarry dust possessing high percentage of silica and lies in abundance as land fill near stone crushers.

[0061] Thus the inventor made possible crystallization of gypsum of required purity level usable in cement manufacturing out of Jarosite or Jarofix individually as also through a method of mixing of both Jarosite and Jarofix by use of number of different non-usable wastes that till date were being landfilled.

[0062] While the mineral gypsum beyond gypsum percentage carried impurities, the chemical gypsum made out of Jarosite/Jarofix was made to possess pozzolanic properties using the present invention, high requisite purity level imparted, is non-hazardous and is useful in cement manufacturing.

[0063] Similarly the inventor made possible crystallization of gypsum of adequate purity level usable in cement manufacturing out of alkaline Red Mud through a method of mixing of Red Mud with use of number of different non-usable tailings/overburden wastes that till date were being land stored.

[0064] No use of any form of energy is required to prepare the final product as the process takes care of chemical and physical properties of wastes and is carried out at ambient temperature without the need of heating or melting. There is no need of firing the mixture at high temperature. In this process of complete conversion of multiple industrial wastes to sustainable alternative usable products if the mixed mass is dried by heating using any means, the process may result in a low purity gypsum product but the other advantages remain the same. Additional advantage invented is that there is no residual waste generation or leftover of any form.

[0065] Therefore complete conversion of multiple industrial wastes to sustainable alternatives is disclosed.

[0066] The process results in an environmentally safe, water in-soluble, immobilized usable crystallized gypsum product possessing pozzolanic properties replacing additional fly ash mixing in cement over the quantities normally mixed.

[0067] One of the preferred embodiments of the said process of the present invention comprise the steps of:

[0068] 1. Mechanically mixing metallurgical waste in the form of aged dry Jarofix containing crystallized Gypsum with freshly generated Jarosite in a proportion of ¼ to ½:1 by weight.

[0069] 2. Addition of toxic gases free waste effluent acidic water generated in zinc industry in a ratio of 0 to 30% by weight.

[0070] 3. Addition of spent H.sub.2SO.sub.4 generated as acidic waste from different industries after filtering the suspended foreign matters in a ratio of 0 to 15% by weight.

[0071] 4. Addition of sodium sulphate MEE salt waste generated in zinc industry, carrying constituents of sodium, sulphate and chlorine in a ratio of 0 to 15% by weight.

[0072] 5. Addition of quarry dust waste in a ratio of 0 to 25% by weight.

[0073] The final product after Lime treatment is crystallized chemical gypsum mass possessing pozzolanic properties.

[0074] As is obvious from the above, automatic gypsum crystallization is carried out by mixing of the wastes, catalysing agents and acidic water additives etc. of a fore mentioned steps carried out in a rotary drum mixer operating on or above ground continuously or intermittently.

[0075] Similar process for acid treated Red Mud mixed with other wastes provides chemical gypsum crystallization possessing pozzolanic properties.

[0076] Therefore a value-added disposal of wastes is achieved by putting to use the water-insoluble non-hazardous cured mass as disclosed above suitable for use as chemical Gypsum for manufacturing cement used in road, building and construction industry.

Novelty:

[0077] The novelty of the present invention lies in developing a process of complete conversion of industrial wastes to sustainable alternative e.g chemical gypsum. No use of any form of energy or industrial activity is required to prepare the final product as the process takes care of chemical and physical properties of the compatible wastes and utilizes them “as is available product” irrespective of any specific climatic or geographical requirement for making the end product. The process is carried out at ambient temperature without the need of heating or melting to make it suitable for use in cement industry as gypsum during cement grinding.

[0078] None of the patents or articles, to the best of the knowledge of the inventor, have disclosed this novel approach.

Inventive Step:

[0079] The inventive step of present invention lies in analyzing the chemical and physical properties of wastes of multiple industries and then developing a suitable activation & catalyzing method to treat compatible wastes together without use of energy in heating or melting, simultaneously providing solution to the excessive moisture present through mix of solid dry wastes and conservation of waste acidic effluent water, developing effective way of reducing the solubility of heavy metals in an inexpensive, safe, and simple manner. The resulting product made out of inert and dead mountains of Jarofix and marble dust or Red Mud and Tailings meets strength and stability tests and found to be non-degradable, easily transportable & used as chemical Gypsum for manufacturing cement used in constructing roads and buildings.

[0080] Therefore to develop a highly economical process, of mechanical mixing Leach free suitable acidic/alkaline wastes of multiple industries on or above ground eliminating contamination risk for any ground water or soil, optimising maximum gypsum crystallization the inventor has put in valuable inventive step unknown or invented in prior arts.

[0081] In the preceding detailed description, the invention is described with reference to two exemplary embodiments thereof. Various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the description. The specification is accordingly, to be regarded in an illustrative rather than a restrictive sense. Thus without analysis, the foregoing will fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention