JP2005104754A5 - - Google Patents

Description

According to the inventor's research on the proposal of Patent Document 2 or Patent Document 3, although the storability can be eliminated, the loose apparent density and the solid apparent density are defined or calculated from these parameters with respect to dischargeability and transportability. It was found that even if the degree of compression is specified, troubles of pipe blockage cannot be avoided. In addition, both methods require a pulverizer or a pulverizer in order to obtain the desired characteristics, which increases the complexity of manufacturing.

The invention of claim 6 is a method for digesting quick lime and producing high specific surface area slaked lime having a nitrogen adsorption specific surface area of 35 m ² / g or more mainly composed of calcium hydroxide, and calcining the carbon dioxide gas to 4 wt% or less. A particle size adjustment step for adjusting the particle size of the quick lime to 0.5 mm or less, and a digestion step for digesting quick lime using an additive that delays the digestion reaction with water. After the digestion step by an aging machine, none of the steps of pulverization, classification and compaction granulation is provided.

Further, among the calcium hydroxides constituting the high specific surface area slaked lime, particles having an average particle size of about several microns are aggregates of self-shaped or semi-self-shaped calcium hydroxide crystals of about submicron. Relatively coarse particles (having an average particle diameter of several tens of microns) aggregated at the time of production are agglomerates of the aggregates. This is based on the results obtained by the inventors using a SEM image of an electron microscope. Due to such a structure, a high specific surface area is maintained even if the relatively coarse agglomerated particles are somewhat increased in the slaked lime particle size constitution. With these findings as a background, the inventors have investigated the adhesion in the piping with respect to the high specific surface area slaked lime having various particle size distributions. the particles in the range of diameter 40μm~200μm 4 5wt% or more, preferably to contain 5 0 wt% or more, leading to the conclusion that the preferred condition for not causing the pipe blockage.

The average particle size of the particles having a high specific surface area slaked lime particle size of less than 40 μm is 10 μm or more. The average particle size of conventional Japanese Patent slaked lime and high specific surface area slaked lime 10μm or less, or in some cases is a 5μm or less, clogging between the bag filter fibers With such a particle size, pressure loss noticeable, the cause of the trouble It is easy to become.

50% coagulation Atsumarido of high specific surface area consumption lime measured by a known powder tester or less, preferably important that 45% or less. This is based on the following reason. With conventional powder testers, discharge from the hopper and transportability evaluation in the pipe are based on parameters such as compression, cohesion, fluidity index, etc. In addition, when considering hopper discharge with vibration and aeration, the degree of aggregation evaluated using a vibrating sieve is preferable. According to specific examples (Tables 3 and 4) to be described later, the amount of adhesion in the pipe is extremely reduced when the degree of aggregation is 50% or less. Therefore, the degree of aggregation may be measured with a powder tester, and high specific surface area slaked lime having an aggregation degree of 50% or less may be selected.

An embodiment of the method for producing the high specific surface area slaked lime of the present invention will be described. In the proposals (eg, Japanese Patent Laid-Open No. 2000-63116 and Japanese Patent No. 3379649) in which the particle size and the like have been defined so far with high-reaction slaked lime or high-reaction calcium hydroxide, calcium hydroxide having different particle sizes are mixed, classified, or pulverized. A process is required. In addition, conventional industrial slaked lime production facilities also have a classification and pulverization step in order to satisfy the particle size regulations. Having these steps leads to an increase in cost, which not only makes the production complicated, but also restricts the production. The microcrystalline or hidden microcrystalline limestone is calcined by adjusting the calcining temperature and calcining time so that the amount of CO _{2 of the} quick lime to be produced is 4.0 wt % or less. Is preliminarily crushed to 0.5 mm or less, preferably 0.2 mm or less, and digested by mixing well-digested water with a conventionally known additive. According to the knowledge of the inventors, the digestion water and quick lime with additives for delaying the digestion reaction of quick lime by adjusting to the above particle size and generating high specific surface area particles having fine pleats and pores The reaction can be made to proceed uniformly. Specifically, by making the particle size as fine as described above, elimination of heterogeneous reaction due to difference in particle size, elimination of heterogeneous reaction due to insufficient uniform dispersion of additives, and extreme aggregation after slaked lime generation The enlargement can be avoided, and the high specific surface area slaked lime having the characteristics of the present invention can be produced by these series of operations and actions without classification, crushing and compaction granulation. For these operations, it is advantageous to apply the method of Japanese Patent Application Laid-Open No. 11-92138 proposed by the inventor, except for new operations such as omission of quick lime particle size and omission of classification and grinding. The digester that causes the digestion reaction may be a dry digester that supplies quick lime and digested water and forcibly mixes them with stirring blades, etc., or puts quick lime into the mixture of additive and digested water A wet digester may be used. In addition, an aging machine for stirring the slaked lime may be provided at the subsequent stage of the digester in order to increase the digestion reaction time and reduce unreacted slaked lime.

The limestone is produced in Okayama belonging to cryptocrystalline fired at Merz furnace, the dry ground product of green produced lime, using Hosokawa high-speed stirring type mixing device, to supply diethylene glycol concentration 100 wt% The mixture was stirred and digested with a continuous digestion reactor to produce high specific surface area slaked lime. Table 1 shows a slaked lime production example together with a comparative example and an invention example.

In Invention Examples 4 to 9, quick lime having a maximum particle size of 0.5 mm or less and a CO ₂ amount of 4 wt% or less was used. In Comparative Examples 1 and 3, the maximum particle size of quick lime was larger than 0.5 mm, and in Comparative Example 2, the amount of CO ₂ was larger than 4 wt% .

Claims (1)

In the method of digesting quick lime and producing a high specific surface area slaked lime having a nitrogen adsorption specific surface area of 35 m ² / g or more mainly composed of calcium hydroxide,
A particle size adjustment step for adjusting the particle size of the quicklime calcined to 4 wt% or less of carbon dioxide gas to 0.5 mm or less;
A digestion step of digesting quicklime using an additive that delays the digestion reaction with water,
A method for producing high specific surface area slaked lime, which is not provided with any step of pulverization, classification, and compaction granulation after the digestion step by a digester or a digester and an aging machine.