sustainable chemistry

Recycling through chemistry

The Research Unit of Sustainable Chemistry at the University of Oulu aims at increasing the exploitation of industrial by-products. In the best-case scenario, waste is processed into an environmentally conscious product: for example, alkaline battery mass can be turned into fertilisers.

Chemistry and industry. The combination brings into mind an image of cut-throat pursuit of gain, with zero consideration for the environment. Professor Ulla Lassi, Head of the Research Unit of Sustainable Chemistry, wants to refresh this perception.

"The principles of green chemistry were created already in the 1980s. Today, nearly all research in this field aims at sustainability, such as replacing oil-based raw materials with bio-based materials. “

 This change can be seen in the Research Unit of Sustainable Chemistry. The research unit was established nominally in 2015, but the first research projects were already initiated ten years ago. Now the unit has completed dozens of them.

"We turn industrial by-products into reusable products, primarily battery chemicals, water treatment chemicals and catalyst materials. We rarely venture outside these,” says the professor.

In other words, this is recycling through chemistry. The initiative and need for research usually come from the business sector; the research unit cooperates extensively with the mining, metal and chemical industries. 

The underlying motivation is the companies’ desire to make financial use of the by-products and process them further for their own use or for sale. The societal steering instruments have also an effect: waste taxes can be avoided by means of recycling, when for example slag categorised as waste is processed into a new product.

Lassi calls the work of the unit “the productisation of scientific research results”. "The result is not always a substance; instead, the product may also be a procedure or a process. For example, if a company’s process includes an expensive and environmentally harmful chemical, we determine a substitute chemical that brings cost savings and a green image for the company. “

 

By-product recycling is also about profitability

 

The recycling of by-products in itself promotes sustainability: recycling saves raw materials as well as energy needed for their primary production. One example is the vanadium-rich slag produced in the manufacturing of steel: the extracted vanadium can be recycled in the steel industry and in batteries.

Vanadium and other metals are included in the unit’s main research field: inorganic materials and process chemistry. Organic chemistry is represented by, for example, a water purification material produced from sawdust. In the organic sector, sustainability is often linked to the issue of avoiding the burning of bio-waste materials to generate energy. According to Lassi, this topic is currently a hot research trend.

"Many bio-based masses that are usually placed in the combustion boilers are now being re-examined, with the aim of finding more advantageous uses for them. One of the best-known examples of this are biocomposites that are produced from the effluents of the pulp and sawmill industry. Energy recovery should be a secondary alternative, if a more valuable use cannot be found. “

Sometimes, the result may be that no applicable results are achieved: in the processing of antibiotic residues in water, the intermediate may be more toxic than the initial material; a water treatment chemical releases harmful substances; there are problems with stability... or the product is simply not profitable.

"A company must consider the bureaucratic jungle and the process ramp-up. In addition, the industrial effluents are generally massive, which means that there would have to be equal demand for products manufactured from them. We are talking about tonnes here, kilograms are usually not that interesting. This is where we sometimes don’t see eye to eye: the scientific aim is to find a new result, but what is worth publishing may not always be of interest to companies.”

 

New recycling method for alkaline batteries may spread world-wide

 

There are several ongoing projects related to the recovery of metals in Finland. For example, a recovery plant is planned in Raahe that would turn slag from the steel plant into ferrovanadium. In turn, Tracegrow, which was recently established in Kärsämäki, utilises alkaline mass made out of crushed alkaline batteries.

The research carried out by the Research Unit of Sustainable Chemistry has played a key role in the emergence of Tracegrow. The cooperation has its roots in battery chemistry research from ten years ago, which included the issue of recycling alkaline batteries: at the time, they were usually melted into slag without further exploitation. However, melting requires a lot of energy, and in Central Europe smelters have been shut down for environmental reasons.

Akkuser Oy, a company that sorts batteries and accumulators, presented the researchers with a problem: there is no procedure for utilising the alkaline battery mass, what to do? Often in sustainable chemistry projects the desired by-product is known since the very beginning; but in the absence of a clear goal, attention is focused on the constituents that are easiest to separate and their uses. In this case, these substances were zinc and manganese, but the uses were more problematic.

"We developed concepts that were functional, but not very cost-effective. During one train journey I racked my brain wondering where I had come across a product containing both zinc and manganese. Then it came to me: they are mineral components... in fertilisers! We had been overthinking the whole problem. The process was simple and did not generate similar waste waters as the previous concepts.”

The simple process (battery crushing, grinding, leaching and solution purification) is now freely marketed by Tracegrow, as is the zinc-manganese fertiliser product separated from the batteries. In the ideal case, this new recycling method for alkaline batteries will spread from Finland all over the world.

However, there are also other components in batteries, such as iron, and there might be demand for zinc and manganese even separated from each other. "It is still worthwhile to consider other forms of utilisation, but for the purpose of achieving industrial production quickly, this was a good solution," says Lassi.

The recycling of battery mass started from lithium-ion battery research carried out at the University of Oulu, and lithium-ion batteries have remained a forte of the research unit already for 10 years.

"Currently this topic is associated, for example, with co-operation with Keliber Oy on the very first lithium mining project in Europe. We are developing primary lithium battery chemical production from a scientific perspective and contemplating the exploitation of by-products.”

 

Examples of the utilisation of industrial by-products

By-product / waste

Utilisation potential

Examples

industrial slags

recovery and reuse of metals

production of ferrovanadium from vanadium slag, alkaline activation and productisation of blast-furnace slag

paper industry sludge

as a precipitating agent in waste-water treatment, as a precipitating agent in the recovery of nutrients

desulphation of mine waters by calcium precipitation, chemical phosphorus binding

nutrient-rich reject waters from biogas plants

recovery of nutrients

recovery of ammoniacal nitrogen, chemical phosphorus binding

crushed batteries and accumulators

recovery of metals through leaching and solution purification

production of zinc and manganese-rich products from alkaline batteries, extracting cobalt and nickel from lithium-ion batteries for recycling and reuse

power plant ash

as a precipitating agent and in the recovery of nutrients

alkaline-earth activated ash in the precipitation of phosphorus, productisation of alkaline-activated ash (several applications)

 

Text: Jarno Mällinen

 

Last updated: 16.11.2018