Toluene and hexane recovery efficiency
Real references in rubber, tapes and coatings
Years of experience with heavy solvents
In rubber, adhesive tape and coating production, the primary solvents are toluene, hexane, heptane and plasticisers, heavy solvents with low water solubility that require steam regeneration in a closed circuit with decanter recovery. We design SRS plants with Donau Carbon – Lurgi Aktivkohle technology installed in this sector since 1981, with capacities up to 150,000 Nm³/h. The recovered solvent returns to production pure, reducing virgin solvent purchasing and diffuse emissions across the plant.
In rubber and coating production, the choice between steam and nitrogen regeneration depends on the solvent's water solubility. For toluene, hexane and heptane with low water solubility, we use steam with decanter separation. For plasticizers we use coalescence filters. For hydrophilic solvents, we use closed-loop nitrogen, with or without vacuum (X-CSR). The downstream distillation system completes the purification and returns the solvent to reuse specifications.
For toluene, hexane, heptane. Steam regeneration, water–solvent separation by decanter. Donau Carbon – Lurgi Aktivkohle technology, licence since 1981.
For hydrophilic solvents such as IPA. Closed nitrogen circuit, zero emissions during regeneration. X-CSR version with vacuum for payback under 3 years.
Batch or multi-column distillation to purify recovered solvent. Distillation separates fractions and returns pure solvent to production.
For low-concentration streams or compositions too variable for recovery. Up to 99% abatement, thermal efficiency up to 95%, Full Electric version available
Toluene, hexane and heptane leave no margin for design errors: they are flammable, require ATEX-certified closed circuits and integrated LEL safety systems. Every Donau Carbon Technologies plant for this sector is engineered to operate safely for its entire service life, not only at commissioning.
SRS technology with Donau Carbon – Lurgi licence is the sector standard for toluene recovery. Adsorber, steam regeneration, decanter and stripping column: a process proven across 40 years of industrial-scale installations.
For adhesive tapes and rubber production, hexane and heptane recovery with steamback technology is documented in plants up to 180,000 Nm³/h. The regeneration circuit is designed to minimise losses and maximise the purity of the recovered solvent.
For coating and adhesive tape plants with mixed hydrophilic and hydrophobic solvents, the X-CSR system with nitrogen and vacuum regeneration handles both fractions in a single compact plant, with zero CO₂ emissions
In the rubber and coating sector, toluene and hexane are subject to particularly stringent emission limits due to their toxicity and flammability. The IED Directive sets BAT-AEL values for the rubber industry; the REACH regulation imposes restrictions on the use and emission of substances such as benzene and toluene. We design every plant integrating these requirements from the outset: LEL systems, paramagnetic O₂ analysers and ATEX closed circuits, without adding compliance as a subsequent layer.
We design to BAT-AEL values specific to the rubber and coating industry, including limits for toluene (< 20 mg/Nm³) and diffuse emissions often unmonitored in existing plants.
Toluene, hexane and heptane have low LEL (Lower Explosion Limit) values. All components in contact with these solvents are designed and ATEX-certified, with integrated inerting systems and LEL control.
The REACH regulation classifies toluene and benzene as substances of concern. We design our systems to minimise fugitive emissions and document compliance with REACH requirements applicable to the production site.
The most frequent questions in the rubber and coating sector concern the choice between steam and nitrogen regeneration, the management of complex mixtures and ATEX requirements for the most hazardous solvents.
Toluene has low water solubility: this makes it ideal for steam regeneration with decanter separation (SRS). Nitrogen regeneration is preferable when the mix also includes hydrophilic solvents such as IPA, or when the objective is to eliminate steam use from the plant entirely.
Hexane and heptane are low-boiling solvents with low water solubility. The SRS process with steamback is the established solution: the solvent is adsorbed on activated carbon, regenerated with steam, condensed and separated from water by a decanter. The carbon is then cooled and dried with air in a closed circuit.
Yes, but it requires a dedicated distillation section downstream of the adsorber. High-boiling plasticisers separate from toluene by distillation: toluene in the light fraction, plasticisers in the heavy fraction. The design requires a specific analysis of the stream composition.
Based on DCT technical documentation, solvent recovery becomes economically viable starting from approximately 300 t/year of treated solvent. Below this threshold, or with very low concentrations (< 1 g/Nm³), thermal oxidation with an RTO is generally the most appropriate solution.
LEL control is integrated into the plant architecture. We use paramagnetic O₂ analysers to monitor oxygen concentration in the nitrogen regeneration circuit, FID and IR sensors for LEL control in the extracted air, and automatic inerting systems in the event of an anomaly.
Solvent recovery with vacuum nitrogen regeneration on a flexible packaging line. Solvent: ethyl acetate. Flow rate: 110,000 m³/h. X-CSR plant installed in 2024.
Solvent recovery on a flexible packaging printing line. Solvents: ethyl acetate and various. Flow rate: 110,000 Nm³/h. Installed in 2021.
Every solvent mixture presents its own specific challenges: varying concentrations, emission peaks, and solvent recovery and reuse. Please let us know the details of your plant.
