Versatile and Simplified Production of High Surface Area-Small Particle Hydrated Limes
- 詳細技術說明
- This technology provides a simple, commercially practical method for preparing hydrated lime with high surface area, high porosity, and low particle size.
- *Abstract
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This technology provides a simple, commercially practical method for preparing hydrated lime with high surface area, high porosity, and low particle size.
DESCRIPTION/DETAILS
This technology provides a cost-effective and simple methodology for producing hydrated lime for use in a variety of industrial applications. Hydrated limes made with this process have high surface areas per unit weight (m2/g), small particle sizes, and greater porosities, making them highly efficient and cost-effective for adsorbent, adherent, and other uses.
How It Works
Lime, prepared directly by calcining limestone, is hydrated via contact with an aqueous solution of an organic solvent that is capable of retarding the rate of hydration (slaking) of the lime. If required, the product can then be washed with another solution of organic solvent in a post-hydration step, designed to displace water prior to drying in order to increase surface area and decrease particle size. These methods are capable of producing a hydrate with surface area greater than 35 mm2/g, and preferably greater than 55 m2/g. Surface areas up to 85 m2/g can be readily obtained.Preferred organic solvents in the hydration and washing steps are lower alcohols, primarily methanol and ethanol. Various calcined limes, provided by commercial kilns, fluidized bed reactors, entrained flow reactors, or other calciners, can be used. To ensure optimal hydration, careful control is maintained over the ratios of liquid to lime and water to alcohol, as well as over mixing conditions (e.g., speed, intensity/power), reaction temperatures, and residence times at each stage throughout the production process.Additional compounds can be added, such as hydroxyl carboxylic acids and/or surfactants, to further retard the hydration rate and lower surface tension, avoid agglomeration, and promote correct crystal size and shape.Hydrates typically have surface areas between 50 and 85 m2/g, with mean particle diameters less than 2.5 microns, and pore volumes of at least 0.25 ml/g.Why It Is BetterThis technology provides a highly versatile approach for making high surface area-small particle size, hydrated lime products. Several methods for preparation of hydrated lime products are provided, each easily adaptable for any of numerous end applications. A proportion of existing lime hydrates, while functional for SO2 removal, typically have less surface area, larger particle size, and smaller pores than the hydrates generated by these methods. This technology provides hydrated limes with highly efficient adherent and adsorbent properties, with anticipated smaller volumes of products.
APPLICATIONS
This technology, as patented and described, has a specific application, namely, desulfurization (SO2 removal) of flue/stack gaseous streams from coal boilers. However, this technology would almost certainly extend to numerous applications including:
- Metallurgy (e.g., manufacture of steel, steel products, magnesium, and alumina)
- Pulp and paper (e.g., sulfate and sulfite processes; bleaching)
- Chemicals (e.g., alkalis, petrochemicals, bleaches, dyes)
- Environmental uses (e.g., treatment of water, sewage, industrial trade wastes, solid wastes)
- Ceramics (e.g., glass, certain potteries)
- Building materials (e.g., specific bricks, concretes, and insulations)
- Protective coatings (e.g., pigments, water paints, varnish)
- Food and food by-products (e.g., dairy, sugar, animal glue, gelatin, and baking industries)
- Lower Production Costs: The use of relatively reactive limes in the hydration process minimizes or eliminates the requirement for external preheating.
- Convenient: The hydration process can be carried out in a single reaction vessel, taking advantage of a series of flexible steps and reaction conditions.
- Time Saving: Fewer processing steps, combined with reduced or eliminated preheating needs, speed production.
- Flexible: Selection of feed lime properties and hydration conditions enables production of a hydrate tailored to the intended industrial applications.
- Lower Application Costs: High surface area, high porosity, and small particle size of the hydrates will reduce the overall quantity of this product for various applications.
- *IP Issue Date
- None
- *IP Type
- Utility
- 國家
- United States
- 申請號碼
- 5492685
- 國家/地區
- 美國
