Composition and properties of acid tar and asphalt produced from acid tar

Characterization of acid tars

“…Frolov et al [18] reported that fresh acid tars contains between 25% and 65% sulfuric acid, a variable organic content of 34-94% resin/oil/asphaltene substances, 5-60% sulfonic acids, and 1-6% carbonxylic acids, and alkali metals originating from caustic waste co-disposed with the acid tars. Puring et al [19] carried out a study on the components of dumped acid tars.…”

Characterization and utilization of acid tar waste from crude benzol processing for environmental sustainability

“…The composition of acid tar is time dependent. This is also supported by [3] when he observed that the percentage of sulphuric acid decreased with time in storage tanks where a solid film had formed on the surface of the acid tar. [21] Have also shown that there is a decline in sulphuric acid in ponded tars when he observed that the composition of the gas after decomposition of pond acid tar had 28.6 mol % of hydrogen sulphide and less than 1.2 mol % of sulphur dioxide.…”

“…The leaching of the waste affects the ground water and the evolution of gases from the waste also affects the atmosphere which might lead to acid rain which will in turn affect surface water. During storage in holding ponds, the chemical composition of the acid tar changed as a result of leaching of the acid from the tar by rainfall, evolution of sulphur dioxide and condensation of the substances present in the acid tar [3]. [4] Also supports this when he observed the inconsistent chemical composition of the acid tar that changes with time due to the reaction of the organic components with atmospheric oxygen and sulphuric acid.…”

“…The processing of fresh acid tar was said to be more difficult than that of acid tar from lagoon due to the high percentages of sulphuric acid [3]. In normal state sulphuric acid mixed with organics does not react with the organic part of the mixture [24].…”

“…Neutralisation is done under controlled temperatures and emissions monitoring since it increases temperature which leads to sulphuric acid and sulphur trioxide evaporating from the mixture if the temperature exceeds 100 o C [25]. [3] proposed a method for the production of paving asphalt: a three key step process which involved neutralisation of the acid tar with technical calcium oxide at temperatures between 90 and 100 o C; evaporation of water from the reaction mass at 100 to 130 o C and oxidation of the neutralised mass with air at 160 to 190 o C in a thermostatic metal reactor with stirrer. In another method by [26] acid tar was converted to asphalt using the thermal cracking method.…”