Market Outlook
HYDRATED LIME MARKET IN INDIA
INTRODUCTION
Hydrated lime is a stable, dry, fine powder produced by the chemical combination of quicklime with water. This is the most concentrated form of lime. Hydrated lime, apart from building industries, is also largely used in chemical industries as a cheapest alkali available. It is consumed in hundreds of solid liquid phase reactions. Hydrated lime requirements exceed the vast tonnage of quick lime required in dry, thermal processes such as sintering, smelting, and fluxing etc. Hydrated lime is used for neutralization, coagulation, dehydration, hydrolyzation and absorption. It is also used as a flux in metallurgy, as a specified lubricant, as a bonding agent, as a filler, as a raw material. Relatively newer industrial uses, such as Flue Gas Desulphurization, have required new product characteristics: from enhanced average fineness, to higher surface area and pores volume.
The present existing manufacturing capacity in the country for the manufacture of hydrated lime is not sufficient to meet the growing demand of its dependent chemical and other industries.
Raw materials, process equipment’s, and the necessary know-how involved in the manufacture of hydrated lime are available indigenously, but are not sufficient to produce quality Hydrated Lime using high reactive quicklime produced from modern twin shaft kilns.
TRADITIONAL DESIGN OF LIME HYDRATION PLANTS IN INDIA
Chemical Reactions:
CaO + H2O → Ca(OH)2 + 15.3 kcal/mole
Molecular weights: 56 + 18 → 74
Therefore, 74 gr. of calcium hydrate shall be obtained from 56 gr. of pure calcium oxide and 18 gr. of water. This means that 132 gr. of Ca(OH)2 shall be obtained from gr. 100 CaO. Therefore, the hydration water represents 24.3% of the finished product and the water-calcium oxide and hydrate-calcium oxide weight ratios are respectively the following ones:
H2O / CaO = 0.321
Ca(OH)2/ CaO = 1.321
The reaction, as shown in the above formula, is strongly exothermic; the quantity of heat developed is equal to 273 kcal/kg Ca
Reaction Speed:
The hydration speed is influenced by the following parameters:
• Quicklime Reactivity: T60.
• Reagents temperature.
• Oxide chemical composition.
• Kind of burning generated by oxide:
• Oxide granulometry subject to the reaction
• Agitation system
• Water distribution
GENERAL LAYOUT OF THE HYDRATION PLANT_INDIAN DESIGN
It is most important to automatically control the feed rate of the water and quicklime to produce maximum high quality hydrated lime of A Grade, especially when we have to hydrate the high reactive lime coming from Twin Shaft Kilns. Further the design should take care of all the points mentioned above.
The Indian designed plants are not very effective to handle the high reactive lime.
MODERN HYDRATOR SALIENT POINTS
Rate of temperature growth in the reaction has a major impact on the finished product.
Finer sizes are reacting so quickly that excess heat cannot be removed as fast as necessary.
Effectiveness of water distribution and product mixing is very important.
Experience says that the rate of temperature growth in the reaction vessel (hydrator) has a major impact on the finished product characteristics.
It is also apparent that finer sizes are reacting so quickly that the generated heat cannot be distributed/removed as fast as it would be necessary to avoid particles “burning” and the consequent delay in hydration (unless chemical additives are used to control the reaction development).
Therefore in the quest for finer particles production, an appropriate gradation must be selected in function of the available quicklime.
The effectiveness of the water distribution and product mixing in the first stage of hydration has also a notable importance.
CONCLUSION
The Indian designers of the Hydration Plant have to carry out extensive developments in the plant design to increase the productivity and quality of the hydrated lime produced.
The existing European Suppliers have developed and incorporated all the modern features into their design and the same have to be opted for the future expansion projects by the Indian producers. The same can be seen in the following video: Enjoy!!
