• Zinc is malleable and a good conductor of heat and electricity.
• It forms a thin dense layer of Zinc Oxide on contact with air (oxygen) which prevents further oxidation of underlying material.
• Zinc is mined in seven Swedish mines and Sweden accounts for approximately 35 percent of Europe’s production.

OCCURRENCE OF ZINC IN SALA
Mainly as the mineral sphalerite (ZnFe)S. The Zn/Fe ratio can vary and as a result the mineral varies in color from yellowish to greenish and dark brown.

SIDE BUSINESS
In 1866, a rather extensive side business was started at the mine, namely manufacturing of lead shot. In this production, one of the mine’s shafts, Torgshaktet, was ingeniously put in use. Torgshaktet, is 90 meters deep. Molten lead was poured through a sieve at the shaft opening and the drops were allowed to fall to the bottom of the shaft. Along the way, they solidified into small spheres. They landed finally in a tub of water and were hoisted up and then polished in a wooden drum with sand in it. Sala prime lead shots were available in many different sizes and where a bestseller in the market.

CORROSION PROTECTION
Steel or iron are our most common construction materials. The construction industry and infrastructure projects use large quantities every year. You find it in bridges, buildings, road barriers and lampposts, but also in small things like bolts and nails.

Steel has many advantages, but one weakness is that it is attacked by the oxygen in the air and forms rust. Rust is porous in nature and over time it eats into the material that eventually becomes weakened. Steel exposed to air must therefore be surface treated.

Zinc’s ability to form a dense layer of Zinc Oxide upon contact with oxygen makes it very suitable as a rust protection. Zinc can extend the life of the steel by between 50-100 years, depending on what environment the steel is in and the thickness of the zinc layer.

HOT DIP GALVANIZING
When hot-dip galvanizing, the cleaned steel parts are lowered into a bath of molten zinc at 460 °C. At the contact surface between the steel and the zinc, a thin alloy layer is formed between iron and zinc, which causes the zinc to stick to the steel surface. The method gives a slightly rough silver matt surface and a very good protection from corrosion.

ELECTROPLATING / GALVANIZING
Galvanizing is a type of plating, where a thin layer of zinc is placed on another metal (often steel) using electric current. The object which is to be coated is lowered into a bath containing zinc ions and electricity is connected to the object. The zinc ions are drawn to the surface and form a thin layer of zinc on the object. The method gives a thin surface layer of glossy, smooth and lightly “flaky” patterned zinc.

BATTERIER / BATTERIES
Zinc occurs as anode in non-rechargeable batteries and have done so for a very long time. Research is ongoing, with promising results to be able to use zinc in rechargeable batteries. Lithium which is otherwise often used in rechargeable batteries are in short supply.

HEALTH
Our bodies need zinc, and the metal and its’ ions are found in every cell of our body. It is critical for the metabolism, hormone balance and the immune system. External signs of zinc deficiency are skin problems, poor wound healing, patchy hair loss and poor appetite. Meat, dairy products, whole grain products and offal foods are good sources of zinc. The absorption of zinc is facilitated by animal proteins. Clams, cheese and nuts are also rich in zinc. Zinc is available as a dietary supplement at pharmacies.

In the Sala mine, the mineral sphalerite occurs parallel to, among other things, the lead mineral galena. In the 19th century, the mine’s management began to investigate whether it would be possible and profitable to mine and refine zinc.

The ambition to produce the metal relates to the explosive science and technology development that took place during the breakthrough phase of industrialization. Zinc had become a desirable product on the market and had several areas of use, not least as an alloy component in countless products.

Modern technology was developed at a rapid pace to succeed in processing zinc in its pure form on a large scale. The Belgian company Vieille Montagne was setting the tone in this movement and started one extensive operation in Åmmeberg, Askersund, in 1857. The company and its engineering pioneers were thus groundbreaking when it came to industrially produce zinc metal in Sweden. The brothers August and Wilhelm Heberle, who in 1888 came to take over the business at Sala mine, had also been active as enrichment engineers in Åmmeberg.

In 1904, AB Sala Zink was formed and took over the business completely. The company invested in among other things the production of zinc white, but it was a major failure as the color pigment never reached good enough quality. That along with a totally failed and very costly investment in new technology for beneficiation of the zinc ore, patented by Gustav de Laval himself, were two central reasons why the mine went bankrupt in 1908.

Zinc is sometimes called the eighth metal because it was discovered and curbed by man much later than the seven metals that were known in Antiquity. Although zinc could not be produced in pure metallic form until the late 18th century it appears in the ancient alloy brass (zinc and copper), though not in pure form.