(12/23/2015) Paranapanema, the largest copper’s producer in Brazil, invested R$ 65 million in the modernization of Sulfuric Acid Unit (UAS) in Dias d’Ávila plant (BA). The UAS is an important part of the company’s process production, as it ensures that the gas generated in the furnace during copper concentrate smelting – mainly sulfur dioxide – is processed and converted to sulfuric acid and clean air, thus avoiding the emission of gases into atmosphere.

The modernization process allowed that UAS become able to treat the gas resulting from the most concentrated complex available on the market today, with more particulate material. So one of the key points was the return of “gas cleaning” equipment – the purification process where the particulate matter is removed from the gas generated by the copper concentrate smelting.

In the “gas cleaning”, the reform included the installation of two heat exchangers, in addition to the existing four, for the reactor cooling process – equipment where is the chemical conversion of sulfur dioxide (SO2) to sulfur trioxide (SO3 ) – and the substitution of the three absorption towers, making the final processing step the SO3 in sulfuric acid 98%.

To receive the new equipment, all with the latest technology, Paranapanema held a number of adjustments in the plant, such as installing a new substation for power supply of heat exchangers and changing the operating system. The procedures were finalized in October and did not affect the operation of other equipment. During interconnection of the new structure to other facilities of the UAS, the company imported sulfuric acid to meet the regular demand of their customers.

Paranapanema’s Bahia plant produces monthly about 40 000 tons of sulfuric acid, which is marketed. “The modernization of UAS Dias d’Ávila is one of the company’s investments in 2015 and reinforces our focus on modernization and maintenance of the plants, reducing the depreciation of assets,” explains company president Christophe Malik Akli.

Understanding the process of producing sulfuric acid

Initial copper’s stages production

Paranapanema purchase the mining of copper concentrate for the copper’s metallic production The copper concentrate is on average 30% of fine copper, mixed with other elements such as iron, sulfur, precious metals (gold and silver) and heavy (such as lead).

The copper’s production consists of a series casting and refining processes that transform the copper concentrate (30% of copper contained) in the metallic copper of high purity (with 99.9% copper contained).

In the first part of the process, the concentrate passes through a high temperature oven (600 ° C to 700 ° C) where is the separation of the compounds: copper melts and is at the furnace bottom; heavy metals settle in another track from the oven and takes place the issue of gas with SO2, which is captured by a pipe that is designed to Sulfuric Acid Unit (UAS).

Sulfuric acid production Steps

1 – Purification: upon arriving at UAS, the gas passes through the line of “gas cleaning”. This season, the gas receives a countercurrent air with a strong spray of weak sulfuric acid (12% to 40%). The goal is to get the particulate matter from the gas.

2 – Reaction: the reactor, the gas with SO2 is transformed by chemical reaction, to SO3. The gas inlet temperature of around 650 ° C, falls to about 350 ° C. The two new heat exchangers (SO3 Cooler) will assist in the cooling process and prevent thermal overload of the reactor.

3 – Absorption in gas absorption towers has a strong spray of liquid sulfuric acid. The SO3 connects to the fluid transforming it into concentrated sulfuric acid 98% and the air comes out clean.

About the main equipment

Line “gas cleaning”

– Tower for abatement of particulate material: antacid built from brick, with external coating of steel, has greater resistance to corrosion and abrasion.

– Solids abatement Vessels: made of resin equipment (fiber) imported antacid with Canadian technology.

Reaction

– Heat Exchangers (SO3 Cooler): made entirely of steel equipment, with Canadian technology, sized for Paranapanema. The four current exchangers performing cooling gas / gas technology (cold gas to hot gas), the two new exchangers added to the plant are air technology / gas and perform cooling with atmospheric air.

Absorption

– Absorption tower for concentration of sulfuric acid: the equipment is the same manufacturer and has the same technology line tower “gas cleaning”, with German brick antacid and external coating of steel.