San Martino di Trecate is Esseco’s operational headquarters and a strategic hub for its industrial and oenological activities. The site houses the company’s corporate offices and an integrated system of production plants, divided into two specialized areas: one dedicated to industrial chemicals and the other to the oenological sector. Additionally, within the plant’s premises is a sulfuric acid and oleum production facility, operated by Essemar S.r.l., a 50/50 joint venture between Esseco Group and Marchi Industriale.
The combustion furnace is the core of our plant. Inside, sulfur is burned with ambient air to produce sulfur dioxide (SO₂) through the combustion reaction:
S + O₂ → SO₂
The oxygen used is sourced directly from the ambient air.
Sulfur is sprayed as fine droplets, which, when exposed to a stream of hot air, ignite within the combustion chamber, releasing a substantial amount of heat.
This heat is utilized to generate high-pressure steam in a fire-tube boiler, where circulating water is converted into steam.
By recovering this thermal energy, we efficiently cool the process gases to an optimal operating temperature. The gas is then scrubbed, purified, dried, and packaged into cylinders for distribution. Alternatively, it can be further processed to produce salts (sulfite and bisulfite powders).
The plant is owned by Essemar, a 50/50 joint venture between Esseco Group and Marchi Industriale established in 2004, and is dedicated to the production of sulfuric acid from elemental sulfur.
In this process as well, sulfur is burned with ambient air, with consequent heat recovery for steam production to be fed to power generation turbines.
Following combustion, the SO₂-containing gas passes to the converter, where SO₂ is converted to SO₃ (sulfur trioxide), generating additional reaction heat that is also transferred to the steam to increase energy production.
After leaving the converter, the gases can either be absorbed in water to produce sulfuric acid, or absorbed in sulfuric acid itself to produce oleum.
In seeking solutions to reduce process effluent disposal costs, we have developed, tested and implemented a new process with virtually zero liquid waste and emissions, while also enabling the production of sodium thiosulfate – a “by-product” that is now finding its market in Europe and worldwide.
The production method, patented by Esseco, was entirely designed and validated at Esseco’s laboratories using a pilot plant. Compared to the Mitsubishi process, our plant achieves a drastic reduction in energy impact and a substantial elimination of environmental impact.
