Mance: Quarry Industry of Southern Indiana 



167 



a uniform size of lump so that the water will act upon it rapidly; 

 second, hydrating the lime, which is accomplished by placing a 

 weighed portion of lime in a hydrating pan holding 1,000 to 

 2,000 pounds. Scrapers in the pan level the lime down to a 

 depth of about 8 inches. The pan rotates under a number of 

 stationary ploughs which are so arranged that the lime is thoroly 

 turned over and mixed every half-revolution. An automatic 

 sprayer which contains a predetermined amount of water is 

 located over the pan and sprinkles the water evenly over the 

 surface of the lime. As soon as the water and lime are thoroly 

 mixed the pan is emptied and a new charge placed in it. The 

 process of hydrating with a high calcium lime does not require 

 over half a minute per charge. Following the process of hydration 

 the product is screened to remove particles of limestone, under- 

 burned lime, and unslaked lumps. The product screened to 

 about 40-mesh is stored in bins ready for bagging and shipment. 



The equipment of a small hydrating plant should include 

 two elevators, one to take the lime from crusher to bin and one 

 to take the slaked hme from the hydrator to the storage bin, 

 as well as a hydrator, a crusher, and screens. 



The above process is known as the batch process. Other 

 methods use machinery which is continuous in operation, the 

 most common being the rotating cylinder, containing screens for 

 discharging the product as fast as it is hydrated. Water and 

 jets of steam are sprayed into the cylinder and accelerate the 

 process. The hme is fed in at the higher end of the cylinder 

 and travels slowly toward the lower or discharge end. The 

 usual capacity of these cylinders is about 8 tons of hydrated 

 lime per hour. They require about 5 horse-power to operate 

 them. 



The lime-hydrating industry is one that is sure to grow in 

 this country inasmuch as the product has many advantages over 

 quicklime for every use in which the caustic properties of the 

 lime are not a necessity. The main advantages are as follows: 



1. Hydrated lime will keep better than quicklime. 



2. It can be shipped in paper bags instead of barrels. 



3. The impurities have l)een removed in the hydrating 

 plants. 



4. It is ready for immediate use. No slaking or seasoning 

 is necessary. 



5. Less is needed to produce an equally strong mortar. 



