Pilot Plant Studies and Process Design for the Production of Calcim-Magnesium Acetate

Chloride salts are commonly used as deicing chemicals in many northern states. These chemicals are corrosive to automobiles, bridge decks and other public structures, and cause considerable damage to plants found near salted roadways. Calcium Magnesium Acetate (CMA) offers potential as an alternate deicing chemical. CMA is a generic term applied to the reaction product of acetic acid and limestone. It is non-corrosive and has no known potential to cause environmental damage. During 1982-194, over 12,000 gallons of saturated CMA solution were produced by researchers in the Petroleum Engineering Department of the University of Alaska - Fairbanks. The raw materials were acetic acid, hydrated lime and native limestone. The product CMA solution was used in road tests in Fairbanks as well as for environmental studies. The results of these pilot plant studies is presented in this report. A process design for the production of 12,000 GPD of CMA from native limestone based on the results of the pilot plant studies is presented. For a grass-roots operation located in Fairbanks, the total capital cost is estimated at $215,000, including site and structure costs. Using current prices for acetic acid, limestone and hydrated lime, a product price of $413 per ton (dry CMA equivalent) is required for a 15% annual rate of return. It should be noted that raw materials costs amount to over 85% of the annual operating costs with capital cost amortization amounting to only 2% of the product cost. The process economics are thus relatively insensitive to changes in capital costs due to process design changes. Moreover, acetic acid cost alone accounts for 70% of the product price. The key to reducing the price of CMA lies in obtaining inexpensive acetic acid.List of Figures - iii List of Tables - v Abstract - 1 1.0 Introduction - 2 2.0 Background - 5 2.1 Costs and Benefits of Deicing - 5 2.2 Salt Use in Alaska - 7 2.3 Alternate Deicing Chemicals - 7 2.4 Properties of CMA - 8 3.0 Production of CMA - 11 3.1 Basic Chemistry - 11 3.1.1 Production from Limestone - 21 3.1.2 Production from Lime - 21 3.2 Sources of Raw Materials - 21 3.2.1 Acetic Acid - 21 3.2.1.1 Liquid Phase Oxidation of Hydrocarbons - 23 Process Description - 23 Laboratory Study - 24 3.2.2 Limestone - 24 3.2.2.1 Literature Search - 24 3.2.2.2 Field Study - 30 3.2.2.3 Data Analysis and Evaluation - 30 3.2.2.4 Conclusions - 30 3.2.3 Lime - 31 4.0 Pilot Plant Studies - 33 4.1 Bulk Production of CMA From Hydrated Lime - 33 4.1.1 Equipment - 33 4.1.2 Raw Materials - 35 4.1.3 Operating Procedures - 35 4.1.4 Quality Control - 36 4.1.5 Material Balances - 37 4.1.6 Observations - 37 4.1.7 Problems - 39 4.2 The Production of CMA From Limestone - 39 5.0 Process Design - 41 5.1 Production of CMA From Limestone - 41 5.1.1 Materials Balance - 41 5.1.2 Process Description - 41 5.1.3 Utilities - 49 5.1.4 Labor - 49 5.1.5 Raw Materials - 50 5.1.6 Economic Analysis - 50 Capital Costs - 50 Annual Operating Cost - 51 5.2 Production of CA from Hydrated Lime - 54 5.2.1 Material Balance - 54 5.2.2 Process Description - 54 5.2.3 Utilities - 59 5.2.4 Labor - 59 5.2.5 Raw Materials - 59 5.2.6 Economic Analysis - 59 Capital Cost - 60 Annual Operating Cost - 60 Conclusions - 65 References - 6