One of the hot topics at the Snow & Ice Symposium in June was the use of liquids - more specifically the use of salt brine, including how to make it, how it works and what it costs. Though most generally agreed on the first two topics, the disagreements surfaced with regard to cost. I heard cost estimates that ranged from 7 to 20 cents per gallon. So, how do you calculate the true cost of salt brine?
To answer that question, we must look at what it really takes to make it - not just the purchase price of the salt being used. Being a creature of habit, I turn to my old pal LEM (labor, equipment and material) for assistance. The following looks at these additional costs and presents figures for the calculations shown below.
Many people miss costs that go beyond the actual brine creation. What labor is involved? Assume a brew master is being paid $15 per hour. Based on that, his real cost is probably around $20 per hour.
An item that is often missed is the loader used to handle the salt. In this case, assume 10 minutes of time moving the salt at $60 per hour for this loader/operator ($10).
Another cost that must be considered is the time it takes to clean the brine maker. With any brine-making process, the best results are achieved when the brine maker is kept clean and insoluble materials are regularly removed. How often this has to be done depends on the quality of the salt being used. How difficult it is to do and how long it takes depends on the brine maker’s design and setup. Not cleaning it eventually will reduce production rates and/or brine quality, and that costs you money. In this case, since there are so many variables to look at in a real situation, assume $2 for this labor cost.
This category includes everything involved in getting set up to make brine: the brine maker, storage tanks, pumps, hoses, fittings, etc. Assume the total setup cost is $50,000 and that it will last 10 years with proper use and regular maintenance. Proper maintenance is estimated to cost $500 annually for LEM. At the end of the 10 years, we intend to replace the system, and estimate it will have a $5,000 value at that time. The expected annual production rate is expected to be 100,000 gallons or more.
In my example, I’m including electricity under equipment. Categorize it wherever you want, but don’t miss the calculation. I’ve included a total cost of $1 for the batch.
Salt. The key to the true cost of salt brine lies in the salt. The purchase price and the quality of the salt are, in most cases, about half the total production cost. Naturally, the more paid per ton and the higher the weight of the insoluble material will result in a higher cost of the finished salt brine.
Cleanliness of the salt purchased and the waste content makes a huge difference in brine production cost. A lower priced salt with lots of trash, dirt and moisture can actually cost more than a quality salt with a higher purchase price not only for brine production but in other uses, too.
To get to the true cost of brine in this example, the purchase price and an estimate of how much of the total weight is going to be unusable in the brine-making process must be included. With a bit of experience with your system and after cleaning out a few times, this number will become apparent. For this example, the purchase price is assumed to be $100 per ton with an estimated 5% loss, making the actual weight of the usable material 1,900 pounds.
To continue the calculations, you must know that for every gallon of 23.3% brine produced, 2.291 pounds of salt is dissolved. So, with 1,900 pounds the number of gallons that can be made is 829.31 gallons. Many will use 870 gallons, which equals perfectly clean and 100% useable salt —something I have never seen except in reagent grade salt.
Water. Water is not free and must be calculated into the cost. Because of the many variables, I used $1 for the total cost of water. When calculating water use, keep in mind that it does not take 100 gallons of water to make 100 gallons of salt brine. Because the salt takes up room, even when dissolved, it takes approximately 90 gallons of water to produce 100 gallons of 23.3% salt brine. Also keep in mind water flow. The number of gallons of brine to be made and the gallons per minute of water feeding the system will feed into costs. The lower the water input, the longer it takes to reach the target.
In this case, the goal is 829 gallons of brine, which means we have to pump 829/1.1 or 754 gallons. At 15 gallons per minute, this will take 50 minutes if all goes as planned.
If you are considering adding brine making to your operations, the next time someone says they are making salt brine for say 8 cents per gallon, odds are they are not taking all of the costs into account. To get the true cost of brine a process as described must be completed. The results presented are in no way intended to reflect the true cost of properly made salt brine. The true cost can only be calculated by going through a process specific to your company.
Dale Keep owns Ice & Snow Technologies, a training and consulting company based in Walla Walla, WA.