Sodium Hydroxide Production from Lime and Sodium Carbonate | Economic Analysis
Caustic Soda Production — Technology Description & Economic Analysis
Sodium Hydroxide is primarily produced by electrolysis of sodium chloride, which generates chlorine as co-product. It may also be a by-product from the lime-soda process, which produces mainly calcium carbonate from lime and sodium carbonate.
This article aims to present a brief process description and a condensed cost analysis of Sodium Hydroxide Production from Lime and Sodium Carbonate.
Process Description
The process under analysis comprises three major sections: (1) Causticization; (2) Sodium Hydroxide Purification; and (3) Calcium Carbonate Separation.
Causticization. Initially, soda ash is conveyed to a dissolution tank, also fed with a wash liquor recovered from a thickening step downstream. Here a strong soda solution is prepared, containing 18–20 wt% of sodium carbonate. In a rotary lime slaker, solid lime is slaked to a dry hydrate using wash liquor recovered from a thickening step downstream. The milk of lime is fed to a mechanical classifier for the removal of unburnt stone, overburnt lime and grit. The purified lime suspension produced is directed to the Causticizer, where a large amount of purified lime causticizes the sodium carbonate solution under agitation, yielding Sodium Hydroxide and calcium carbonate. The lye suspension, containing the sodium hydroxide produced, overflows to the 1st thickener, where the calcium carbonate settles and is separated as a sludge, generating a clear lye containing most of the Sodium Hydroxide.
Sodium Hydroxide Purification. The clear lye is concentrated in an evaporator, yielding a 50 wt% caustic soda solution. The suspension is then allowed to settle, recovering the soda solution.
Calcium Carbonate Separation. The cake from the 1st thickener is fed to two other thickeners, along with wash water, for further separation of remaining caustic soda from the sludge. The precipitated calcium carbonate obtained is partly dried, deagglomerated to the desired particle size and sold as by-product. The remainder is sent to a kiln, in which calcium carbonate is converted back to calcium oxide and carbon dioxide is generated. The calcium oxide obtained is reused in the process.
Cost Analysis
The economic evaluation of industrial processes is a valuable support tool for a myriad of activities and studies, such as screening and assessment of investment options, preliminary evaluation of the economic potential of emerging industrial processes, rough assessment of the economic feasibility of industrial ventures, cost estimates double-checking, preliminary budget approval, research planning, and so on.
A detailed cost analysis for the manufacturing of Caustic Soda was developed by Intratec based on a plant constructed in 2019 Q1 in the United States with the capacity to produce 100,000 metric ton per year of Caustic Soda. The table below presents a few economic figures related to the process “Sodium Hydroxide Production from Lime and Sodium Carbonate”.
Where,
“Raw material costs” are the costs related to the raw materials directly consumed by the process to make the final product.
“Working capital” is defined as the funds, in addition to the fixed capital, that a company must contribute to a project, for getting the plant into operation, and meeting subsequent obligations. It includes raw materials inventory, products inventory, in-process inventory, supplies and stores, accounts receivable and accounts payable.
Main Reference
[1] Intratec. 2019. Sodium Hydroxide Production from Lime and Sodium Carbonate, Advanced Edition. Available at: www.intratec.us/analysis/sodium-hydroxide-e21a
Caustic Soda Production Processes
To learn more about processes related to Caustic Soda production, visit: www.intratec.us/analysis/caustic-soda-production-cost
About Intratec Commodity Production Costs Reports
The report Sodium Hydroxide Production from Lime and Sodium Carbonate is part of a series of reports prepared by Intratec approaching the production costs of commodities spanning a diverse range of industries: Oil & Energy; Fertilizers & Gases; Olefns & Derivatives; Aromatics & Derivatives; Alcohols & Organic Acids; Polymers; Inorganic Chemicals; Food & Nutrition; Metals & Mining; and Pharmaceuticals.
For information on all Intratec reports visit: www.intratec.us
