Spent acid treatment

Spent acid treatment.

Jacobs has developed a number of processes to purify and concentrate sulfuric and/or nitric acid from a variety of sources. Our processes focus on concentrating the acid, recovering valuable by-products, and minimizing effluents and energy consumption. In many cases, several process options are combined to provide a tailor-made process.

Jacobs' spent acid plants and equipment solutions are specifically custom designed to each clients’ individual needs. Our capabilities range from engineering studies to design and complete turnkey projects.

Below are examples of our process options. Please contact us if your application is not listed, and we can further discuss the development of a process that fits your needs:

Sulfuric acid denitration

Spent sulfuric acid from nitration processes (e.g. di-nitro toluene/tri-nitro toluene production) or from the production of concentrated nitric acid contains various amounts of NOx, nitrous acid and nitric acid. Jacobs' sulfuric acid denitration process removes these components and recovers the impurities as weak nitric acid which can be re-used.

Sulfuric acid stripping

Some spent sulfuric acids contain impurities that can be removed by air or steam stripping. Common examples are mono-nitro toluene, di-nitro toluene, methanol, methyl chloride and chlorine. Our process can incorporate additional equipment to separate and concentrate valuable byproducts.

Sulfuric acid pre-concentration

Some spent sulfuric acids contain impurities (e.g. ammonium sulfate) that cannot be removed and prevent the re-use of the spent acid. Common examples are spent acid from methyl/methacrylate and acrylonitrile production. Jacobs' pre-concentration system removes a substantial amount of water from the spent acid before it is thermally decomposed in a sulfuric acid regeneration (SAR) furnace. This can reduce the SAR plant size or lower energy requirements.

Sulfuric acid concentration (SAC)

Sulfuric acid is concentrated using a vacuum evaporation process. The sulfuric acid concentration (SAC) process can be designed to produce sulfuric acid up to 98 wt%. Large capacities are obtained by using multiple stages in series. For dilute sulfuric acid, it is also possible to use a multiple effect process to minimize energy consumption.

Nitric acid denitration

Spent nitric acid from the hydroxylamine production process contains nitrous acid. Our nitric acid denitration process removes the nitrous acid as NOx, which can then be returned to the originating process or recovered as weak nitric acid.

Weak nitric acid concentration

Dilute nitric acid can be concentrated using a single or multiple effect distillation process to commercial concentrations of 65-67wt%. Our process is designed to minimize nitric acid decomposition and produces a water white product.

Strong nitric acid concentration

Weak nitric acid can be concentrated using an extractive distillation process to any desired concentration. Jacobs' process utilizes either sulfuric acid or magnesium nitrate to manipulate the nitric acid/water azeotrope. Depending on the application the process can also include a bleaching step to remove NOx and provide a water white product.

Spent acid from chlorine drying

In chloralkali plants, concentrated sulfuric acid is used to remove moisture from the chlorine gas prior to compression. This drying process creates a dilute acid stream that is saturated with chlorine. Often, this acid is disposed of as a waste stream or neutralized. Jacobs offers an alternative, proven process for the concentration of this spent acid allowing the acid to be recycled to the drying towers.