The Essential Role of Metals in Modern Technology and Sustainability

Metals have become indispensable in our current world. From building and construction materials, various means of transport to electronics and household items such as cooking utensils. We unconsciously use metal objects every day without realizing what it takes before the metal is processed into a utensil.

The production of solar panels, electric cars, and wind turbines in particular requires enormous quantities of various metals, often much more than the use of fossil fuels. This includes rare metals such as cobalt, lithium, and neodymium, but the need for aluminum, cadmium, copper, gallium, indium, graphite, iron, lead, nickel, silica, tin, and zinc is also increasing sharply. Due to the enormous scale of solar and wind farms and electric cars, the need for these types of metals has also increased explosively.

Metals are rarely found in pure form in nature. Metals are usually mined in the form of ores, which are converted into the pure metal form in metallurgy. Examples of this are the extraction of cast iron from iron ore using blast furnaces or the electrochemical conversion of bauxite into aluminum.

Manufacturing pure metals from their ore is, in many cases, a cost- and energy-intensive process. Each metal has its own kind of process. As is known, iron is by far the most common metal and needs heavy industry to convert it into steel. Different processes, from the blast furnace, oxygen furnace converter, hot and cold rolling mills, up to the hot dip galvanizing line, are necessary for a usable end product.

Other metals like aluminum are extracted from alumina by electrolysis. Alumina is purified bauxite, which is basically aluminum ore. The process of electrolysis involves using an awful lot of electricity to break down electrolytes to form base elements. To make this process possible the alumina must be liquified before the electrolysis to let the electricity pass. Aluminum is one of the metals which is extracted from its ore by this method.

Zinc is made by using a combination of a smelting process and an electrolytic process. A mixture of zinc-containing concentrates or secondary zinc material, such as zinc oxides, is used as raw material for the roasting plant. The concentrate is burned, releases impure zinc oxide, sulfur dioxide and heat. The impure zinc oxide is dissolved in sulfuric acid to form a zinc sulfate solution. The contaminants, like other metals, are removed from the solution as much as possible. In the final phase, zinc metal is extracted from the purified zinc sulphate solution by means of electrolysis.

Copper ore first undergoes a flotation process to purify the ore, this is necessary because copper ore normally contains less than 1% copper. This process releases various types of other metals, ranging from nickel and cobalt to various precious metals. The ore is then further purified using a roasting process, and copper concentrate is converted and concentrated to a higher purity via a converter, which is basically a chemical process. A final step towards pure copper is achieved by electrolytic refining.

The benefits of metal recycling are enormous; reuse of these types of materials is crucial to prevent soil depletion. Global supplies of metal ore are also limited and finite. By reusing metals, no ore needs to be extracted. This is, of course, beneficial for the living environment and nature. Processing extracted ore into reusable metal saves a huge amount of energy: for ferrous metals, this can be up to 75%; for aluminum, even 95%; for zinc, this is still 60%; and for copper, approximately 85%.

In a world where climate change and carbon dioxide emissions are central every day, energy savings are, of course, the most important reason for recycling metals. By reusing and recycling metal and iron materials, gains are also made in this area, and the burden on the environment and air quality is reduced. Consider the following average savings: up to 86% less air pollution, 40% reduction in water use, and therefore more or less 76% less water pollution. Finally, the major advantage of metal recycling is that this material can be recycled virtually 100%. So little to no material is lost during the recycling process.

According to the Industrial Emissions Directive 2010/75/EU (Integrated Pollution Prevention and Control) for ferrous and non-ferrous metal production and processing, scrubbers are among the best available techniques to reduce emissions. Ravebo has designed wet gas scrubbers to absorb and reduce virtually all common emissions in the metal industry. The scrubbers are designed according to a so-called open spray system, in which the absorption takes place in the very fine droplets generated by special nozzles. The big advantage, aside from high efficiency, of this type of scrubber is a very low pressure drop, which means that energy consumption is low.

Another strong point of this type of scrubber is its ability to decimate both particulate matter and chemical components simultaneously to acceptable emission limits. The scrubbers are so versatile that the installation can be constructed from several sections in series so that the entire spectrum of contaminants can be removed and the temperature of the waste gas can be drastically reduced through adiabatic cooling. The construction and materials used in the scrubber have been developed in such a way that incoming gas temperatures of up to 900 °C can be used.

The scrubber actually converts a gas-side problem into a liquid-side problem. The contaminants carried by the off gas are absorbed by the washing liquid, causing it to become contaminated. To avoid draining a lot of water to stay within the emission limit values ​​on the gas side, facilities have been installed that allow the water to be recycled.