Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

The mine safety cap lamp is one of the important factors on working efficiency of miners in the underground face. In the cap lamp laboratory of Engineering College, Seoul National University, the authors conducted many basic experiments about effective usage of Edison R-4 cap lamps and their charging equipments. Instead of the electrolytes specified by Edisons Safety Cap Lamp Co., it has been attempted to make electrolytes of the cap lamp batteries by using KOH and Li(OH) solutions, and to test their chacteristics of charging and discharging time.The experimental procedures and results are as follows.a) The experimental procedure and special remarks in process are;1) In making electrolytes using KOH and Li(OH), the range of the specific gravities of potassium hydroxide solutions in known to be;First-fill electrolyte for 1.228 to 1.230Refill electrolyte for 1.212 to 1.216Renewal electrolyte for 1.248 to 1.250The first-fill electrolyte consists of a 21% solution of potassium hydroxide in water with 50grams of lithium hydroxide to the liter of solution. The refill electrolyte consists of also a 21% solution of potassium hydroxide with x grams of lithium hydroxide; the amount of lithium hydroxide is made approximately equal to the quantity found after formation in the original electrolyte. The renewal electrolyte consists of a 25% solution of potassium hydroxide with 15 grams of lithium hydroxide per liter. 2) Depending on the working time, the specific gravity of the electrolyte in a cell will gradually decline to 1.160 when it should be dumped out and replaced with renewal electrolyte.3) Electrolyte, when exposed to the air, absorbs carbon dioxide to form a white hard carbonate which collects in valve and on cell cover.4) Lamprooms should be kept a temperature not less than 50°F since batteries will temporarily lose capacity, and give shorter burning time when allowed to stand in lower temperatures.b) The experimental results obtained are;1) The model R-4 cap lamp batteries using electrolyte of Edison Co. are the best way to be charged at 1.8 amperes for a period equal to 3/4 of burning time, but with above a- (1) electrolytes, cap lamp batteries should be charged at 1.8 amperes for period epual to 3/4 of burning time. Therefore it is apparent from our experiments that the charging time of our batteries system is required considerably longer time than that of model R-4 batteries.2) After battery has been resolutioned, it is favorable to charge 12 hours at normal rate of 1.8 amperes. It is thought that the charging will cause severe evaporation of water and weakening of electrolyte. Therefore it will be necessary to fill more frequent water and will shorten the period required for renewal of electrolyte.