• A PLACE FOR - INSPIRATION AND CHAT

    A PLACE FOR

    INSPIRATION AND CHAT

Tin

Posted November 6th 2017

Tin is a chemical element, belonging to group 14 of the periodic table. Its symbol is Sn, which comes from the Latin stannum, and it is what we call a post-transition metal. It is commonly used in alloys, including bronze and pewter, as well as in the plating of steel to add a corrosion resistant layer.

Malleable and very ductile, tin is a silvery white coloured metal that has a relatively low melting point of 232 degrees Celsius (the lowest within that group in the periodic table). As it is so soft, it is unusual for tin to be used in its pure form and instead it is most commonly seen in alloys. Bronze is one of the most popular alloys we see tin in, produced since as early as 3000 BC. It is comprised of around 12% tin and the remainder of copper with a small amount of other metals such as aluminium and nickel. Tin is also used heavily in pewter, which can contain as much as 90% tin alongside copper, lead and antimony.

Due to a high level of corrosion resistance, tin is often used as a coating for lead, zinc and steel. Combined with a low level of toxicity this makes tin a perfect material for us in food packaging, such as tin plated steel cans.

Tin is also popularly used with lead as solder, which is used in electric circuits as well as piping systems. Following the European Union Waste Electrical and Electronic Equipment Directive and Restriction of Hazardous Substances Directive, which was introduced on 1 July 2016, the content of lead has decreased which leads to problems when trying to replace it, such as a higher melting point. Tin pest can sometimes occur in lead-free solders, which causes the deterioration of the tin at low temperatures.

Today the London Metal Exchange (LME) is the primary trading place for tin, although other tin markets include the Kuala Lumpur Tin Market (KLTM) and the Indonesia Tin Market (INATIN). Tin has historically had a high price especially during the years of agreements between producer and consumer countries. The International Tin Council have tried to keep this stable by buying stockpiles during periods of low price and selling these again during periods of high price in an effort to keep the price steady. However, the stockpile was never large enough and during the years of 1956 to 1985 tin prices mainly rose. The recession of 1981-82 had a dramatic impact on the tin industry with consumption reducing and the ITC stumbling into debt. This culminated in it reaching its credit limit in 1985 and tin being delisted from trading on the LME for three years. Following this, the ITC was dissolved and the price of tin has become more stable.

Today, William Rowland sells tin in the form of pellets and sticks.

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Where is all the gold?

Posted October 25th 2017

The journal Nature recently published an article that argued the gold and silver found on Earth should be much more abundant than they are. Whilst both metals can be found scattered throughout space, they are relatively rare to find on Earth compared to other elements, and the lack of gold in particular has been a growing concern amongst the mining industry. Whilst the metal has always been scarce, it is being found less and less often which will certainly mean an increase in price as time goes on.

Bernard Wood, a geologist from Oxford University, argues that ‘The silicate Earth is strongly depleted in moderately volatile elements (such as lead, zinc, indium and alkali elements) relative to CI chondrites, the meteorites that compositionally most closely resemble the sun’. His paper studies the lack of gold and silver found on the planet, concluding that the way it was formed is the cause of this.

‘Earth’s Volatile Contents Established By Melting And Vapourisation’, as the paper is titled, looks at the formation of the earth and argues that the gold that would have been present at one time turns to gas once it reaches a particular level of temperature. Using a furnace, Wood studies the effects of heat on a model version of an early Earth, using temperatures of up to 1,300 degrees Celsius, as well as adding elements such as carbon dioxide, carbon monoxide, basaltic rock and zinc oxide to the process, to mimic the formation of the planet.

‘Our experiment shows that melting processes explain the pattern [of volatile depletion] perfectly’, concluded the study. ‘We find that the pattern of volatile element depletion in the silicate Earth is consistent with partial melting and vapourisation rather than with simple accretion of a volatile-rich chondrite-like body’.

gold bricks

The most powerful magnet in the world

Posted October 15th 2017

Although magnetic materials and magnetic fields are naturally occurring, the most powerful magnet in the world is man-made. Reaching a huge 100 tesla, the magnet is over 2 million times more powerful than the Earth’s own magnetic field, and sits in the National High Magnetic Field Laboratory (NHMFL).

In March 2012, researchers at the facility were able to claim that they had created the strongest magnetic field ever, that was non-destructive. The power of the magnet is over 100 times more powerful than a typical junkyard magnet often seen moving cars or heavy pieces of equipment, and 30 times stronger than the magnetic field that comes from an MRI scan.

The Los Alamos facility is one of three sites that form the NHMFL and the current home of the colossal magnet. Weighing in at 18,000 pounds, and with a huge 1,200 megajoule motor generator, it provides researches with a unique tool to use in their study of materials and the effect of magnetic fields on them. Although other attempts have been made to build similar magnets, none have successfully been able to emit a magnetic field without destroying themselves. As such, the magnet at the Los Alamos site is called a multi shot in reference to its ability to be used over and again – as often as once an hour.

The magnet is composed of four electrical circuits and is surrounded by liquid nitrogen, which keeps it at a cool -198.15 degrees Celsius. This is inside a container known as a dewar and it is used to keep the magnet cool and prevent it from overheating. The magnet is so strong that it also emits a loud shrieking sound when in use, caused by the electrical current modulation. It can only be kept on for a few seconds.

magnetic waves

Asteroid Mining

Posted October 6th 2017

Asteroid mining is the removal of raw materials from an asteroid. It is not something that has yet been accomplished, but there have been many proposals and theories on how this could become possible and there are several companies in existence dedicated to this purpose, including Deep Space Industries and Kepler Energy and Space Engineering.

There are thousands of asteroids that pass close to the Earth, and could potentially be used for the purpose of mining. The materials that can be contained in an asteroid include gold, iridium, cobalt, tungsten, aluminum and nickel, as well as numerous others that we use on a daily basis. With modern industrial processes continually depleting out natural reserves of materials such as zinc, tin, lead, silver, gold and copper, the possibility of them being found elsewhere is certainly appealing and one which we should not dismiss. Whilst this may sound quite far-fetched, Chris Lewicki, the president of Planetary Resources and one of their chief engineers, puts it into perspective. ‘It is natural to doubt when you don’t know much about it. Most people read the headline and make assumptions. We are only repeating what has been done throughout history, just in a new environment.’

The new environment, however, that we are looking at is one which is hostile and dangerous, and that we have barely begun to discover. Despite this, those behind the concept of asteroid mining believe that it has the potential to shape our economy for the next century and will be revolutionary in developing our knowledge of space. They emphasise the importance of not only bringing materials back to Earth, but using them in space for further construction and discovery. Space Foundation, a global non-profit organisation believes the results could be ‘revolutionary in benefits to space exploration, and all of us on Earth’.

asteriod mining

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Recycled metals – What do we use them for?

Posted September 26th 2017

In the society of today, recycling is more prevalent than ever. We are encouraged to recycle whenever we can, but what happens to the things we do recycle? Where do they end up?

Metal is one of the major materials that can be recycled. Aluminum, iron, steel, copper and brass can all be recycled and reused, more than once, to make new products. Not only is it easy to use the scrap metal to make new products but it also reduces the need for new mining. It makes economical sense to recycle and reuse materials where possible and by doing this we can cut CO2 emissions, air and water pollution. When you bear in mind that the average household uses over 600 food tins and 380 drinks cans per year, it isn’t difficult to see how this energy can be saved.

How scrap metal is used differs depending on the metal. Some of the most commonly recycled metals are aluminum and steel, which can be recycled over and over again without losing their quality. The benefit of this is that the recycled metals can be used to make the same items. They are commonly used to make new food packaging – often the packaging will carry a mark to let you know that it has been recycled, and it can take as little as 8 weeks for a tin to be bought at the supermarket, used, recycled and make its way back to the supermarket. Most food tins contain at least a percentage of scrap metal if they are not made from 100% recycled metal. Recycled aluminum is also commonly used in the construction industry, alongside scrap iron, particularly in the building of bridges and roads. Other uses include the manufacture of aircraft, cars and even home furnishings.

recycled metals

The History of Metal in Sheffield

Posted September 15th 2017

The city of Sheffield is well known for steel manufacturing and metallurgy. From the 18th century onwards it was quickly established as one of the main industrial cities in the UK, although it was recognised for the manufacture of knives as early as the 14th century with a notable mention from Chaucuer in The Reeve’s Tale.


Ay by his belt he baar a long panade,

And of a swerd ful trenchant was the blade.

A joly poppere baar he in his pouche;

Ther was no man, for peril, dorste hym touche.

A Sheffeld thwitel baar he in his hose.

Round was his face, and camus was his nose;


The location of the city, situated amongst a multitude of rivers and streams, made it ideal for water powered industries to flourish and in the 1600s, Sheffield became the hub of cutlery production in England, outside London. In the 1740s, Benjamin Huntsman, who lived just outside Sheffield in the town of Handsworth, invented a version of crucible steel process that would produce better quality steel than had previously been possible. His method involved a coke-fired furnace that could be heated to a staggering 1,600 degrees °C. Clay crucibles would first be heated, before adding an alloy of carbon and iron known as blister steel. After 3 hours in the furnace the pots were removed, and impurities skimmed off, before the molten steel was cast and cooled. Also notable at this time was the invention of Sheffield plate by Thomas Boulsover, a combination of layers of copper and silver that is very strong and was used to produce a multitude of household goods. Because there was a large amount of copper, covered with a thin coating of silver, items were able to be produced at a far lower cost than if they were made only of silver.

In 1912, Harry Brearly discovered stainless steel in his research laboratory based in Sheffield. The metal was marketed as Staybrite in England by Firth Vickers and was used in the new entrance to the Savoy Hotel in London in 1929. Although when he applied for a US patent Brearly found that someone in the US had already registered one, he was able to join forces with Elwood Haynes to create the American Stainless Steel Corporation.

As steel began to be mass-produced the population of the city grew exponentially from the 18th to the 20th century, going from 60,995 in 1801 to 577, 050 in 1951. Although the industry has since declined Sheffield is still recognised as a key contributor to the metal industry and continues to manufacture specialist steel today.

sheffield metal history

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Casting Metals

Posted September 7th 2017

‘Casting’ is a process used in metalworking where a metal in liquid form is poured into a mould and allowed to cool in the cavity to form a specific shape. It is a commonly used process for making complex shapes as the use of the mould allows for great detail and it is more economical than other processes might be. Once the metal has solidified it is removed from the mould and is known as a casting. Items commonly produced by casting include pieces of jewellery, sculptures, tools and some weapons.

The process of casting has been used for thousands of years, but it has been steadily refined and modern casting can now be broken down into two distinct sub-categories – expendable and non-expendable casting. In the expandable casting process, a temporary mould is used that cannot be reused, whereas in non-expendable casting the mould can be reused. This is then further differentiated by which material and which pouring method is used.

There are a variety of materials that can be used for casting, including non-metals such as sand and plaster. If using metal, the most common ones are iron, aluminium, steel, copper and zinc. When casting metals, a non-expendable method of casting is commonly used. For example, permanent mould casting uses a reusable mould, usually also made of metal, to cast metals such as iron, zinc, tin, aluminium and copper, amongst others. Usually, gravity is used to fill the mould, but vacuum or gas pressure can also be used. Another popular method is die casting which pushes molten metal into a mould using high pressure. Die casting usually uses non-ferrous metals such as zinc, copper and aluminium alloys, but it is also possible to use ferrous metals, although they are less common.

It is possible for defects to occur during the cooling period, also known as the solidification process, such as gas porosity and solidification shrinkage. Because of the nature of the casting process, it is difficult to do anything to prevent these from occurring so proper steps should be taken throughout the process to combat these. Shrinkage, for example, usually happens when the metal cooling in the mould is less dense in its liquid form, meaning as it cools to a solid the density decreases. In order to prevent this a suitable metal should be used.

casting metal

The origin of the steel skyscraper

Posted August 23rd 2017

Although they are undoubtedly still impressive, skyscrapers have become a common feature of modern cities that we have become accustomed to seeing on busy skylines such as New York and London. Constantly evolving, they push the limits of architectural design, with the Burj Khalifa pushing an imposing 828 metres in height. However, this is a far cry from the humble origins of the modern skyscraper which began in 1884 with a small structure of only 10 storeys in Chicago.
The Home Insurance Building of Chicago, designed by William Le Baron Jenney, was the first structure to utilize a steel skeleton on the interior to support its weight. This is one of main factors a building must have in order to be classed as a skyscraper in modern architecture so despite the relative lack of height, the Home Insurance Building is what kickstarted the evolution of skyscrapers.
Jenney was the man who came up with the idea of relying on the strength of metal to support his vision, rather than stone. At the time the building was constructed this was unheard of and the city of Chicago halted construction of the building at one point to investigate its stability, so new was the idea. Although Jenney initially thought an iron frame would be the best option, he switched this to steel half way through the project, which would go on to become an incredibly important decision.
As architects began to incorporate steel and other metals into the construction of their buildings, it became possible to start pushing the limitations of height as buildings became stronger and more stable. Although the first skyscraper may only have been 10 stories tall, todays skyscrapers are defined as having at least 40-50 floors and are usually higher than 100 metres, although many go far above this. Modern skyscrapers do not have load bearing walls as they used to, due to their height, and instead architects must consider how to counteract things like wind and seismic loads through their structure. Most modern skyscrapers use a tubular design, a concept made popular by designer Fazlur Rahman Khan in the 1960s, as this allows them greater flexibility in their design rather than having to confirm to a rectangular or box shape. There are many famous examples of both designs still in existence.
skyscraper

How does heating metal affect its properties?

Posted August 14th 2017

Applying heat to different metals can have a dramatic effect on them and can completely alter their structural, magnetic and electrical properties. There are several methods that can be used to change metals through heat, in order to enhance more favourable qualities, and the varying methods that are used will depend upon the metal and the desired result.

Thermal Expansion

Heating metal can increase its volume, length and surface area, as the heat displaces atoms from their usual position which alters the structure. This is known as thermal expansion and the amount of growth depends on the metal. Examples of this can be seen in everyday life when things such as pipework in bathrooms and the plumbing of houses expand and contract in hotter and cooler months. A common side effect of this is burst pipes.

Magnetism

Iron, cobalt and nickel are all naturally magnetic materials, or ferromagnetic materials. When heat is applied to them it can reduce their natural magnetic properties to a point so low that it is completely gone. This point, which is different for every metal, is known as the Curie temperature. For cobalt this is 1110 degrees Celsius whereas Nickel is much lower at only 330 degrees Celsius.

Resistance

Some metals are able to effectively reduce, or halt, the flow of an electric current. This is known as resistance and how resistant a metal is depends on how quickly electrons are able to pass through it. When metal is heated, electrons can gather energy more quickly which allows them to move faster and thus increases the level of resistance as they are more likely to scatter and collide. Similarly, a drop in temperature can result in a drop in resistance as the electrons move more slowly.

Different heat treatments include the processes of annealing, normalising, hardening and tempering. These are used to alter the properties of various metals and gain an end result better suited to the intended use of the metal. The aim may be to strengthen, soften, increase ductility or provide uniformity to name a few.

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What is galvanizing?

Posted August 5th 2017

Galvanizing, or galvanization, is the term used for the process of applying a layer of zinc to steel or iron, in order to create a protective coating. It is commonly used as a method of protecting metals from corrosion as the layer of zinc prevents the metal from oxidizing.

There are several ways in which galvanizing can protect the base metal. Firstly, it creates a protective layer which protects the base metal from corrosion by offering sealed protection from the surrounding environment. The zinc will prevent elements such as water getting through, unless it is scratched or damaged badly enough to expose the metal underneath. The outer layer of zinc usually slows the corrosion of the base metal too, preserving its longevity through ‘galvanic corrosion’.

There are several methods of galvanizing.

Hot-dip galvanizing

The method of hot-dip galvanizing involves submerging the base metal in molten zinc, to produce a thick and robust ‘outer shell’. This method is quick to perform, which makes it economically attractive, but it is not suitable for use on everything and can be inconsistent in the results it produces.

Pre-galvanizing

Pre-galvanizing has similarities to hot-dip galvanizing and involves cleaning sheet metal before immersing it in hot, molten zinc. Large steel coils can be quickly galvanized using this method, with more reliable and uniform results than hot-dip galvanizing. However, once the coil is cut to produce smaller pieces of metal uncoated edges are left exposed.

Electro-galvanizing

Electro-galvanizing utilises an electric current to deposit zinc ions on the base metal, as opposed to melting the zinc like other methods. The zinc ions are deposited on the positively charged base metal, and in a similar way to pre-galvanizing this method is popularly used on large rolls of sheet metal. This method offers a consistently uniform coating, but it is generally thinner than the results obtained using the method of hot-dip galvanizing.

Although the process of galvanizing offers a lengthy period of protection, some damage is inevitable if exposed to the elements and over the years the coating will degrade. If proper measure are taken, such as regular paint coatings and maintenance then the life of the galvanized steel can be prolonged.

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