A young researcher from the Perm Polytechnic Institute has developed a method for extracting rare and expensive metals from monitors and screens, which has no analogues in the world.
The group of scientists presented the first results of the research in the E3S Web of Conferences magazine. On April 15, many countries around the world celebrate the Day of Environmental Knowledge. By 2020, 53.6 million tons of e-waste have accumulated worldwide, including non-working electrical devices and smartphones. Their number is growing every year, and in ten years this figure may reach 74, 7 million tons. In Russia alone, 1.6 million tons of electronic waste is generated every year.
“Today, the average lifespan of mobile phones and computers is shrinking to around two and six years. The devices then become waste that cannot be recycled. As a result, they pollute the environment. Therefore, we have proposed a method that will allow rare and expensive metals to be returned to the production cycle,”says Anastasia Chugainova, a postgraduate student of the Environmental Protection Department of the Faculty of Chemical Technology, Industrial Ecology and Biotechnology of the Perm Polytechnic University.
E-waste contains many rare and expensive metals such as indium, gold, cerium and erbium. In addition, they contain other beneficial elements: aluminum, arsenic, boron, barium, calcium, chromium, copper, iron, potassium, magnesium, molybdenum, sodium, nickel, lead, tin, antimony, strontium and zinc.
In particular, the screens are coated with indium and tin to produce a touch screen. Most smartphones are equipped with a display made from a mixture of aluminum oxide and silicon dioxide. It is additionally hardened with potassium ions to increase its strength. Rarer elements are being used to color the display and resist UV radiation, the researchers said.
Rare metals are now mined from natural sources, but these reserves will last for 20 years. Their content in the source is 0, 001 to 0, 1 percent. Extraction generates more than 90 percent of additional impurities. By recycling electronics, you can get more useful material and reduce the hazard class of waste. Separation of a specific metal from the entire stream will allow it to be returned to the production cycle, and not buried at MSW landfills, as is happening now.
“We leach metals into a solution that needs to be brought to the required pH level. Microscopic algae Chlorella Vulgaris, Chlorella Sorokiniana, Chlorella Spirulina, and Scenedesmus sp. absorb them from screens and monitors. Then we burn the algae, and the metals remain in the ash residue. We are now "training" algae to "selectively" extract rare metals. Our group has already determined the necessary conditions for the processing of screens and the extraction of metals, explains the biotechnologist.
The project of the young researcher was supported by the Innovation Promotion Foundation under the UMNIK program (2019 - 2021). In addition, she completed a one-year internship on this topic at the Technical University of Hamburg (Germany) with the support of a scholarship from the President of the Russian Federation (2018 - 2019).
According to scientists, the development may be of interest to consumers of rare metals - manufacturers of electronic equipment and enterprises of the machine-building and metallurgical industries. In addition, the technology can be applied at plants for the extraction and production of rare metals and at landfills for municipal solid waste.