THECUBAREVIEW 2» 



It is necessary to start the Inirning some days before the factory is to boffin grinding in 

 order to insure a s\ipply of both Hine and carbon dioxide. After the burning lias ])rogressed 

 for soTue time samples of the burnt rock are withdrawn an<l tested by i)lacing them in a beaker 

 with a small qviantity of water. If the lime has been ])roi)erly burned, it will be comijletely dis- 

 solved during this test and leave no sediment. That portion of the lime which has been well 

 burned should then be removed and a similar amount of material introduced at the top. After 

 the work is well under control the filling and removing may go on continually. 



Lime in Cane-Juice Clarificalion. 



High-grade lime finds its most extensive use in the clarification of sugar-house ])roducts 

 subseciuent to the crystallization of sugar. Since the object in view in the ai)plication of this 

 material to cane juices is to effect the ]>recipitation of the im])urities therein contained in order- 

 that a pure juice may be had for concentration, it is obvioiis that the lime should not contain 

 many impurities. Another reason why a high-grade lime should be employetl is that magnesium 

 forms an impurity of ordinary lime and when cane juice containing this material is boiled, com- 

 pounds of the magnesium are deposited on the evaporator tubes forming hard scales which are 

 very difficidt to remove. These incrustations have the effect of lowering the coefficient of heat 

 transmitted from the steam to the boiling juice, thus retarding the work of concentration as. 

 well as causing an extra outlay of labor. 



Another objection to the use of impure lime is that iron is often contained tlierein and this- 

 combines with various impurities in the cane juice forming dark-colored i)roducts which are 

 almost impossible to remove with the ordinary methods of clarification. This impurity is 

 receiving greater attention every day due to the adoption of methods for the manufacture of 

 white sugar directly in one continuous process at the plantation factory. The majority of the 

 impurities in the lime are more or less soluble in cane juice, and while they may be present in 

 such small amounts as not to perceptibly lower the coefficient of purity of the juice, yet the ill 

 effects exjjerienced in impairing the color of the clarified juice are of far more importance than 

 the purity coefficient alone, especially when plantation white sugar is manufactured. For the- 

 above reason it is important to select a high-grade Hme for the p\iri>ose. 



The quality of the lime used for cane-juice clarification depends to a large extent upon 

 three factors, namely, the quality of the original lime rock from which the lime was derived, the- 

 proper bvirning of the rock to convert it into the oxide form, and the treatment given the 

 finished product from the time it was burned until prepared for the factory. 



While it is practically impossible to find deposits of any magnitude containing only high- 

 grade material,yet it is a comparatively simple matter to separate the inferior material from that 

 used for the manufacture of Ume. The rock must first be broken into pieces before it may be 

 conveyed to the Idln, and during this work the sorting should be done. The impure rock may 

 usually be detected by the difference in the color as well as in the formation. The presence of 

 iron is invariably detected by a red or brown color. Where the kiln is located some distance 

 from the sugar factory, immediately after the lime has been burned, it should be placed in air- 

 tight containers to preserve it in the oxide form until ready for use. Used kerosene cans and 

 metallic drums answer very satisfactorily for this purjiose and where these receive the proper 

 care they may be used a number of times. If the lime is not properly protected it first ab- 

 sorbs moisture and later combines with the carbon dioxide from the air forming the original 

 class of material, limestone. This imparts the efficiency of the lime and requires that more 

 material be em.ployed to neutralize the acidity and precipitate the mipurities in the juice. It 

 assists to some extent, however, in mechanically removing the various suspended impurities- 



In preparing the lime for the clarification of cane juices a weighed portion is put into a 

 measured quantity of water and thoroughly mixed. During this time a great deal of heat is 

 evolved. The resultant mass is known as milk of lime and various amounts of this material are 

 added to the cane juices depending upon the acidity as well as the amount of im])urities present. 

 In some systems the lime is applied as the oxide in a finely pulverized form. This system must 

 be handled with care, however, in order to prevent dark-colored glucose combinations from 

 forming, which would impair the color of the finished sugar imless the molasses film is completelj^ 

 washed away from the crystals. 



