Abstract:
A method of producing a hydrated lime. The process hydrates quicklime in conjunction with standard means of hydrating lime. The resulting hydrated lime has highly reduced contents of calcium oxide and magnesium oxide. The hydrated lime has little to no remaining reactivity when placed in contact with water after the process. The hydrated lime can is with stoichiometric volumes of water as required to fully hydrate the quicklime and water mixture as well as with volumes beyond the calculated stoichiometry with some potential for remaining water left after the process without the potential for lime putty or a wet hydrate as the result.

Description:
BACKGROUND OF THE INVENTION 
     “Lime” is a general term used for calcium-containing inorganic materials, in which carbonates, oxides and hydroxides predominate. Lime is used in large quantities as building and engineering materials (including limestone products, concrete and mortar) and as chemical feedstocks, among other uses. Lime is typically derived from mined limestone or chalk, which are composed primarily of calcium carbonate. These rocks may be crushed or pulverized and chemically altered through various processes. “Burning” (calcination) converts lime into the highly caustic material known as “quicklime” (calcium oxide, CaO). Through subsequent addition of water, quicklime is converted into the less caustic (but still strongly alkaline) slaked lime or hydrated lime (calcium hydroxide, Ca(OH)2). The process of converting quicklime to slaked lime or hydrated lime is called slaking of lime. 
     The chemical reactions describing the production of high calcium or dolomitic based lime hydrate are as follows: 
     
       
                 
         
             
             
         
      
     
     Quite often the terms Hydrated Lime and Slaking are used interchangeably; however there is a definite and distinct difference between the two terms. Hydrated Lime is defined as a process whereby approximately stoichiometric amounts of water and lime react to form a product, hydrate, which is a dry powder; i.e. it contains less than 1% free moisture and is handled as a powder. In contrast, slaking is defined as a process whereby lime is reacted with an excess amount of water to form a lime slurry which is handled as a liquid. Hydrated lime is a very well-known and understood material that has been used for many years as an additive into many different industrial applications. It is formed when quicklime or calcium oxide (CaO) comes into contact with water. When water is added to quicklime an exothermic reaction takes place which converts the CaO to Ca(OH) 2 . This exothermic reaction is known to drive off the water the calcium oxide reacts with in a very extreme rise in temperature while releasing evaporated water. Once the material has reacted it becomes very stable and is thereafter used in many applications from civil engineering work, additives in food, to stabilize soils and foundations, and the like. 
     The quality of raw lime materials vary with the quality of the rock formations from which it is mined. Limestone deposits differ in quality by many aspects. One of the most measurable differences is the magnesium content of the deposit. As magnesium content increases to higher levels, a different grade of lime is the end result. This high magnesium content lime is called “dolomitic lime” and is preferred in the production of certain end products. 
     The production of hydrated lime starts at a limestone quarry. The limestone, CaO 3 , is mined as a mineral from the characteristic quarry for the desired final product use. The limestone is processed to a fineness required for the energy intensive kiln process wherein CO 2  is driven off and the result is a fine white product comprised mostly of CaO and a percentage of MgO (dependent on the mineral deposit within the quarry). Since the CaO and MgO are very reactive with water, the material is either immediately hydrated on site at a hydration facility or stored in a low moisture environment. 
     There are many lime hydration facilities throughout the world. Although there are many specific and unique ways to hydrate specific quicklimes, the most common ways involve one of two types of process. The first is a non-pressure environment which is most commonly used for high calcium quicklime where the magnesium oxide content is less than 7%. The second involves high pressure process wherein the higher magnesium oxide content limes (where the magnesium oxide content is more than 7%) are hydrated more fully than without the use of pressure. 
     The amount of pressure can be modified to aid in the hydration of the MgO, which is harder to hydrate than CaO. In addition, the amount of water that can also be modified to aid in the hydration process. Slaking is often used for the process which involves the use of greater than stoichiometric amounts of water beyond what is needed for the full reaction and results in a liquid-lime slurry. 
     The improved process is a modification to the dry hydration process. 
     BRIEF SUMMARY OF THE INVENTION 
     A method of producing a super hydrated lime (SHL) by either a batch or continuous process as a process incorporated into an existing lime hydration facility or as a stand-alone process. The process hydrates quicklime in conjunction with standard means of hydrating lime within or without a controlled pressure environment. The resulting hydrated lime has highly reduced contents of calcium oxide, magnesium oxide and a carbon chain bonded to the structure giving it qualities much different than hydrated limes manufactured by current production processes. Therefore, as a hydrated lime the final hydrated lime has little to no remaining reactivity when placed in contact with water after the process, as compared to the state of the art, and proves superior for use in many applications for which hydrated lime is used at present and allows for more tolerance for error within the production process. The super hydrated lime is formed through the process of weighing stoichiometric volumes of water as is required to fully hydrate the quicklime. The next steps are placing a surfacant and quicklime in a mixer, mixing the surfacant and quicklime mixture in the mixer, and then adding water to the mixture to form a super hydrated lime. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The FIGURE is a schematic diagram of a system that performs a method of forming hydrated lime. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The super hydrated lime process  10  involves the incorporation of an additional step to the hydrated lime production process that is not presently performed. Upon completion of the formation of quicklime  12 , through the quicklime formation process, the quicklime  12  is typically conveyed to a storage silo  14  to await delivery as quicklime  12  to customers or for immediate use in the hydration process. The super hydrated lime process  10  adds a circuit to the standard quicklime hydration process. 
     The super hydrated lime process  10  is as follows, the quicklime  12  (CaO) leaves the storage silo  14  mechanically, such as through a conveyor  16 . The quicklime  12  (CaO) is conveyed to a first measuring mechanism  18  which weighs or measures a known quantity of quicklime  12 . This known quantity of quicklime  12  is added to at least one mixer  20 . Preferably, depending upon size, the mixer  20  is a high shear mixer that can range anywhere between 5 and 200 rpm. 
     The process includes a liquid surfactant  22 , which is stored in a first storage tank  24 . The liquid surfactant  22  is conveyed to a second measuring mechanism  26  which weighs or measures a known quantity of liquid surfactant  22 . This known quantity of liquid surfactant  22  is added to the mixer  20  through a first dispensing device  28  that in a preferred embodiment is a set of nozzles. 
     The surfactant  22  is added in a proportion required by the chemistry of the quicklime  12  to ensure the proper and complete coating of the maximum surface area of the quicklime  12  (CaO) possible. The amount of surfactant  22  added is varied as the grain size of finished quicklime  12  (CaO) varies. 
     In addition, the manner in which the quicklime  12  and surfactant  22  are added to the mixer  20  is also varied. In one arrangement, the full quantity of quicklime  12  and surfactant  22  are added at the same time and mixed together. In another arrangement the full quantity of the quicklime  12  or surfactant  22  is added to the mixer  20  while the other material is slowly added to the mixer  20  while mixing occurs. In another arrangement the quicklime  12  and surfactant  22  are both added at controlled rates to the mixer  20 . In one arrangement quicklime  12  and liquid surfactant  22  are added to the mixer  20  in a continuous flow process, where raw materials are continuously going into the mixer  20  and mixed quicklime  12  and liquid surfactant  22  are continuously flowing out of the mixer  20 . In another arrangement, quicklime  12  and liquid surfactant  22  are added to the mixer  20  in a batch process, where raw materials are added in batches to at least one mixer  20  and mixed quicklime  12  and liquid surfactant  22  are removed from the mixer  20 . 
     Mixing continues until the surface area of the quicklime  12  is coated with surfactant. While a standard mixing time can be calculated, mixing time can vary depending on variation in the inputs to the process  10 . Mixing time depends upon the grain size of quicklime  12  (CaO), quantity of quicklime  12  (CaO) added, impurities in the quicklime  12 , amount of surfactant  22  added, the type of surfactant  22  used, manner in which the quicklime  12  and surfactant  22  are added to the mixer  20 , the speed, design or manner of operation of the mixer  20 , or any other variation in the process including variation in mixer type that satisfies the aforementioned variables. 
     Next, the quicklime  12  and surfactant  22  mixture is conveyed to a third measuring mechanism  30 . The quicklime  12  and surfactant  22  mixture is then weighed or measured and a specified quantity of the quicklime  12  and surfactant  22  mixture is added to a hydrator  32  for initiation of the hydration reaction. Hydration occurs in the hydrator  32  at atmospheric pressure. Alternatively, pressure is added to or contained within the hydrator  32  such that the hydration occurs at higher than atmospheric pressure. 
     Water, or another hydrating liquid,  34 , is stored in a second storage tank  36 . The liquid  34  is conveyed to a fourth measuring mechanism  38  which weighs or measures a known quantity of liquid  34 . This known quantity of liquid  34  is added to the hydrator  32  through a second dispensing device  40  that in a preferred embodiment is a set of nozzles. 
     Water or another hydrating liquid  34  is added to the quicklime  12  and surfactant  22  mixture within the hydrator  32 . As water  34  is added, a chemical process occurs within the hydrator  32 . The heat of the hydration process bonds the carbon chains of the surfactant  22  and quicklime  12  along with the water  34  creating a modified hydrated lime or super hydrated lime  42 . The modified chemistry of this material creates a modified product having similar characteristics when added to water as an oil/water mixture. Where the surface tension between the resulting hydrated lime  42  is very high due to the modification of the surface chemistry. The resulting hydrated lime  42  is fully hydrated to the point that the hydrated lime  42  is 90% to 100% insoluble in water and unmixable with water directly. 
     A properly administered process will result in a 100% insoluble and hydrophobic powder. A process whereby residence times or volumes of additives are not specifically adhered to nets a 90% insoluble hydrophobic powder. 
     In some arrangements, depending on certain variables in the process  10 , resulting hydrated lime  42  is conveyed to a finishing tank  44 . Finishing tank is any containment or storage device with mixing that will allow for the final finished product, the hydrated lime  42 , to be completely hydrated and therefore allow for the completion of the reaction. The finishing tank  44  may be required in certain existing lime hydration facilities if the existing hydrator  32  does not allowing for the proper time to hydrate the super hydrated lime  42  completely. 
     The liquid surfactant  22  can be a blend of one or more oils that do not mix with water. Both stability requirements and economics govern the best or optimal blend of surfactant oils to be required for specific applications. Specifically, the following types of surfactants work in this process: alcohols, preferably ethanol or methanol in conjunction with small proportions of detergents with dimethyl siloxane used as an antifoaming agent within the surfactant blend. 
     It is also possible to blend various cationic and anionic enzymes at varying percentages to modify the chemistry for specific applications as required for the final end product. Surfactants preferably do not contain any percentages of water. 
     Thus the hydrated lime  42  consists of by volume 0.5-40% (% of total water) surfactant (surface modifier agent mixture) of which 50%-99.5% by volume is oils, including petroleum or non-petroleum oils, new or recycled, 0.5%-50% by volume as catalyst/enzymes and surfactants and detergent regarded for the specified hydration a varies with the surfactant. A water additive in one embodiment is added in multiple steps for both hydration control and quality control of the hydrated lime process. Alternatively a water soluable dimethyl siloxane as an additional coating agent or performance enhancer can be added as desired within the product. 
     The additional step involved in this process can be incorporated directly into an existing lime hydration facility or can be situated at an offsite production facility. This ultimately depends on the economic benefit derived from the process. Quick lime  12  (CaO) has a much higher density (approximately 60 pcf) than does super hydrated lime  42  which has a density of (approximately 30 pcf), so transportation economics can govern which model is better for the placement of a facility.