Posts Tagged ‘Platinum’

Types of platinum thermocouple wire

Platinum thermocouple wire

A thermocouple is quite simply a sensor for measuring temperature, with many applications from central heating boilers to jet engines. Thermocouples use the reaction of two dissimilar metals to measure temperature variation. The types of metal involved vary according to the temperature range in which the thermocouple operates.

Some thermocouples use relatively inexpensive alloys such as nickel, chrome, iron and aluminium. The thermocouples we’re interested in, known as Types B, R and S, use platinum – a rare and expensive material that is one of the noble metals (which also include silver and gold).

Platinum, rare and valuable

Platinum has the chemical symbol Pt and the atomic number 78, and is twice the density of silver. One of the rarest elements on Earth and extremely valuable, it is mined mostly in South Africa. As an indication of its value, the crown worn by Queen Elizabeth the Queen Mother, as Consort of King George VI, had a frame made of platinum. Though the crown was undoubtedly spectacular, the platinum frame added significantly to its weight; a solid six inch cube of platinum weighs as much as an adult man.

We don’t expect you to send us the Queen Mother’s crown for valuation! However, though the platinum wire used in thermocouples is a relatively small diameter, its value makes it well worth selling to Gold-Traders.

Platinum qualities

Why platinum? It cannot be oxidised, withstands most acids, has high resistance to corrosion and high temperatures, and is electrically stable and an efficient conductor. In thermocouples, platinum is often combined in an alloy with rhodium, a chemically inert transition metal which is also part of the platinum group.

Types of platinum thermocouple

The ratio of platinum to rhodium depends on the type of thermocouple.

Type B Thermocouple Wire

For a Type B thermocouple, one conductor will be 70% platinum, 30% rhodium, while the other will be 94% platinum, 6% rhodium. Type B thermocouples are used for very high temperature measurements, with a usable range of around 800°C to 1800°C.

Type R Thermocouple Wire

A Type R thermocouple will have one conductor with 87% platinum, 13% rhodium, and the other conductor 100% pure platinum. It’s used for temperatures up to 1600°C, in applications such as the steel industry.

Type S Thermocouple Wire

The Type S thermocouple can also withstand heat up to 1600°C, and has one conductor that’s 90%, 10% platinum and the other 100% pure platinum. A typical application for Type S is providing the calibration standard for the melting point of gold (1064.43°C). It’s also used in pharmaceutical and biotechnology applications.

Scrap Thermocouple Prices

  • Type B: £ (70% conductor) & £ (94% conductor)
  • Type R: £ (87% conductor) & £ (100% conductor)
  • Type S: £ (90% conductor) & £ (100% conductor)

Selling Thermocouple Wire

Unlike other dealers, the prices we quote are the prices we pay. We have no hidden deductions and don’t charge testing or refining fees.

To sell your thermocouple wire, please complete our claim form. Once submitted, you’ll be asked to print a copy for signing and we’ll give you full instruction regarding packaging and postage. All packages are dealt with on the day of receipt, Monday to Friday. If you have any other questions, please feel free to give us a call to discuss.

February 28th, 2013 1 Comment » Platinum |

Simple Platinum Hallmark Guide

Platinum hallmarking was introduced in the UK in 1975 as a result of legislation brought about by the Hallmarking Act of 1973. Prior to this date, items containing platinum would often carry no markings or simply ‘Plat’ or ‘Platinum’ and would be of varying purity.

A typical platinum hallmark

All platinum items weighing more than 0.5 grams must now carry a valid hallmark when sold in the UK. The photo on the right shows a typical hallmark. A platinum hallmark will consist of 3 compulsory and 3 optional stamps.

This post is a simple platinum hallmark guide, which we hope you find useful. If you have platinum to sell, please see our up-to-date scrap platinum prices. We also publish our scrap gold prices and our scrap silver prices.

The three compulsory platinum marks

Sponsor Mark

Also referred to as the makers mark, the first stamp in the photo indicates who submitted the item for hallmarking. Each sponsor (maker) has their own unique stamp.

Fineness Mark

The third stamp in our example photo is the fineness mark. This tells you the precious metal content, expressed in parts per thousand. There are four recognised standards of platinum:

  • 850 (85% pure)
  • 900 (90% pure)
  • 950 (95% pure)
  • 999 (99.9% pure)

When identifying an item as being platinum, it’s important to check the shape and contents of the fineness mark. If the shape is anything other than what is shown below, it isn’t platinum. As you can see, our ring is 950 platinum.

Platinum fineness

Assay Office Mark

The assay office mark tells you which assay office tested and hallmarked your item. There are now four assay offices in the UK:

Assay Offices

Assay offices

 Optional platinum hallmarks

The following 3 marks are all optional. Under hallmarking legislation, there is no compulsorary requirement to show these additional marks, however they are often shown.

Traditional Fineness Symbol

If your platinum item has a purity of 950 or 999, it may display the traditional orb mark. In our example photograph, you can see the second stamp is the traditional fineness symbol.

Platinum fineness orb symbol


Date Letter

Date letters are optional and therefore not always seen (as in our example photograph). The date letter tells us the year the item was hallmarked. As date letters were standardised across all assay offices from 1975, it’s quite easy to read. Below is a chart of all date letters from 1975 onwards.

Hallmark Date Letters

Standardised UK hallmark date letters from 1975 onwards

International Convention Mark

An International Convention Mark is sometimes shown within the hallmark. It is a mark recognised by all member countries of the International Hallmarking Convention.

Platinum convention mark

Convention mark

Testing platinum

Without a valid hallmark, most jewellers and small scale gold buyers will not be able to accurately test the purity of platinum jewellery. Due to its inherent inertness, traditional ‘acid’ testing can only help determine if an item isn’t platinum, however you can’t for example differentiate 900 and 999 platinum.

High-end and specialist precious metal dealers use XRF (X-ray fluorescence) testing to accurately identify the platinum content of jewellery. Inductively coupled plasma, optical emission spectrometry is used by assay offices during the hallmarking process.

March 14th, 2011 23 Comments » Hallmarks, Platinum |

Sell Platinum Thermocouple Wire

Platinum thermocouple wire

Used in laboratories and in scientific instruments, platinum thermocouple wire is often used for measuring temperatures in-excess of 2000°C.

Due to its high value, thermocouple wire should always be recycled. You can sell your platinum thermocouples to Gold-Traders and receive payment on the day we receive your package.

You can check our scrap platinum prices, which are always up-to-date. The rates we display are the prices we’re paying on that day. There are no hidden fees or deductions to be taken off the price.

If you’re unsure as to what type of thermocouple wire you have, we’ve compiled a short article to summarise the varieties of platinum thermocouples and the prices we pay.

To proceed, please fill out our claim form and follow our simple instructions in relation to postage and packing.

March 9th, 2011 2 Comments » Platinum |

Platinum Crucibles

A crucible is a container made from a material that doesn’t melt easily and used for high temperature chemical reactions. If you’re looking to sell platinum crucibles, Gold Traders has the expertise to handle them.

Platinum crucibles offer very high temperature strength. Its contents can be heated in excess of 1000°C without the crucible melting.

Being a noble metal, Platinum does not oxidise or corrode, thus does not interfere with the chemical reaction occurring during the heating process.

Inevitably, a Platinum crucible will reach the end of its life at some point. Once it becomes cracked or misshaped beyond repair, it must be replaced.

Gold-Traders purchases unwanted and damaged platinum crucibles. Our scrap platinum prices page is regularly updated and shows the rates we’re currently paying.

We deal with everything on the day of receipt (Monday to Friday), so if you send us your unwanted crucibles today, you’ll have the funds in your bank account tomorrow. If you would like to proceed, please complete our claim form.

September 10th, 2010 No Comments » Platinum |

Interesting Facts about Platinum

  • Many of the worlds most precious gemstones, including the Hope Diamond, have Platinum settings.
  • During World War II, non-military use of Platinum was banned in the United States, as it was deemed a strategic metal.
  • Platinum is hypo-allergenic. This is the reason why Platinum has so many medical and dental applications and a large factor in it’s popularity as jewellery.
  • While Platinum was known to the pre-Columbian people and discovered by modern man in the 1700’s, it was not possible to produce the metal in quantity or work with it until the advancement of technology in the nineteenth century.
  • When Queen Elizabeth the Queen Mother was coronated as consort to King George VI, the frame of her crown was constructed in Platinum.
  • The annual production of Platinum is about 130 tons.  While this seems like a substantial number, it pales in comparison when you realise that around 260 tons of steel are used in U.S. manufacturing operations every day.
  • To refine just one ounce of pure platinum, around 10 tons of ore must be mined. The refining process takes around 6 months to complete.
  • All of the Platinum ever mined would barely fill a 25 cubic foot (7.6 cubic meter) box. The block would weigh over 16 tons.
  • 90% of the worlds annual supply of Platinum is extracted from four mines.  Three of these mines are located on the continent of Africa.
  • 50% percent of the Platinum produced annually in all mines is used for industrial applications.
  • The melting point of Platinum is 1,769°C and its boiling point is 3,827°C.
  • The density of Platinum is 21.45 g/cm3, that’s 11% more than gold and about twice the density of silver.

Platinum : The Versatile Precious Metal

Platinum has become a symbol for exclusivity in our time. The rarity of this precious metal has caused its name to be used in the identification of record setting musical albums, high limit credit cards, special DVD collections and other services or items that people wish to designate as being better than their counterparts. While the metal does not see the wide use that other precious metals, such as gold or silver, Platinum is a versatile metal that has come to be regarded highly in the global culture.

What is Platinum?

Platinum is a precious transition metal from group 10 of the periodic table with the chemical symbol, Pt, and an atomic number of 78. The color of Platinum is grayish white, often resulting in a mistaken identification as the metal, Silver, a coincidence which led to the metals common name, Platinum, a derivation of the Spanish word, Platina, which is translated to mean ‘Small Silver’.

Platinum has an extremely high melting point of 2041.4 Kelvin and a boiling point of 4098 Kelvin. Platinum also has one of the highest densities of metals found in nature, falling into place at 21.45 g·cm-3 when measured at room temperature. It will not oxidize in air but can become corroded when in the presence of cyanides, halogens and sulfur, as well as certain caustic alkalis. Platinum forms chloroplatinic acid when dissolved in aqua regia but it cannot be dissolved with either hydrochloric or nitric acids.

Platinum occurs naturally in the Ural Mountains, the continent of Africa, the South American country of Columbia and a few of the western states of North America. The metal ore is usually found in the presence of other metals from the Platinum Metals group (Palladiun, Ruthenium, Rhodium, Iridium & Osmium), as well as gold, silver, nickel and copper.

When Platinum was first discovered in South America by the pre-Columbian tribes as a naturally occurring alluvial deposit, it was largely overlooked, although these tribes did find uses for the silvery looking metal in some areas, as artifacts created from a white gold and platinum alloy have been found in the region of modern day Esmeraldas, Ecuador. To understand why the precious metal was not more widely used, we can look to the writings of the Italian, Julius Ceaser Scaliger, who described a then unknown noble metal which no fire had been able to liquefy. The unknown noble metal he referred to was Platinum.

In modern record, two men are credited with the discovery of Platinum. The first was Charles Wood. Wood was a British national and, as a metallurgist, he was naturally intrigued by the samples of Columbian Platinum which he found on the islands of Jamaica during the year 1741. He found the metal to be so interesting that he sent samples to his colleague, William Brownrigg, who then tested and studied the metal for the next nine years before presenting his findings to the British Royal Society in 1750. This report of a previously unknown precious metal with an extremely high melting point and other unique characteristics brought out a surge of interest among European scientists of the day.

The other individual who has been credited with the discovery of Platinum is the Spaniard, Antonio de Ulloa. As a general, explorer, author and astronomer, Ulloa was a highly regarded individual.  His scientific achievements earned him an appointment to the French Geodesic Mission, an ambitious project to measure a degree of meridian at the equator. This mission brought Ulloa to Ecuador in the year 1736, where he first encountered Platinum at some point during his eight year stay in the country.  On his return trip, Ulloa’s ship was captured by British forces and he became a political prisoner. His charming personality and scientific knowledge quickly earned him favor, however, and even gained him a position on the British Royal Society and safe passage back to his native country.

Following the discovery of Platinum and its introduction to the British Royal Society, the European scientific community was set ablaze with the desire to know more about this new metal.  Various individuals studying Platinum’s different attributes worked diligently at unlocking its secrets. In 1772, Carl von Sickingen was the first to succeed in creating a malleable platinum alloy.  Twelve years later, in 1784, the first Platinum crucible was invented by Franz Karl Achard, who used Platinum’s known property of fusing with Arsenic to achieve the process.

Nearly 40 years after Ulloa’s return to Spain, Charles III of Spain awarded a complete library and laboratory to Pierre-François Chabaneau to devote to the study of Platinum. Through trial and error, Chabaneau eventually succeed in producing 23 kilograms of pure Platinum in a malleable form.  This discovery led to what is now known as the “Platinum Age” of Spain, when Chabaneau and his business partner began manufacturing expensive Platinum ingots and utensils for sale.

To demonstrate that Platinum has yet to tell all of its secrets, in 2007, almost three centuries after Platinum’s original discovery, German scientist, Gerhard Ertl was awarded the Nobel prize for his research into the catalytic oxidation of carbon monoxide over platinum, a discovery which led to the creation of the catalytic converter, a pollution reducing device that is standard on nearly all gasoline and diesel powered vehicles in the world.

Mining and Processing Platinum

The mining and processing of Platinum is a long process which can take up to 6 months to complete. With the rarity of the metal in platinum containing ores, it is necessary to extract and process anywhere from 7 to 12 tonnes of ore to produce one ounce of pure Platinum.

Platinum is gathered by mining, followed by the processes of extraction, concentration and refining. By-products of these processes are Iron, Sulphur, Copper, Nickel, Cobalt, Gold and Palladium.

In addition to mining, Platinum is often recycled from discarded products. The largest source of recyclable Platinum is the catalytic converters used on vehicles and these items can command a hefty price when sold to recycling centers who melt the recyclable Platinum with Iron or Copper. The recycler then leaches the resulting alloy to remove excess metals and impurities before sending the resulting material for further processing by a refiner.

The Uses of Platinum

Platinum has been used for a wide variety of purposes by man. While original uses included jewellery, ornamentation and utensils, Platinum has expanded its usefulness far beyond this limited scope.

Due to Platinum’s resistance to high temperatures, it commonly finds application in defense systems such as missile nose cones and military aircraft applications, where durability under extreme temperatures is essential.  In civilian applications, Platinum is used in high temperature furnaces, corrosion resistant electronics and for pollution reduction as a major component of catalytic converters.

Medical uses of Platinum include dentistry, drugs to fight cancer, precision instruments and laboratory testing equipment such as Crucibles and Thermocouples. Platinum is also used as a component to alloyed metal to make non-corroding replacement parts for the human body, such as joint replacements.

Platinum is also prized for its investment value. For those seeking to invest in Platinum, it is notable that the value of the metal is prone to extremes. It is considered to be a more volatile investment than gold and can often see an extreme price spread of over $1,500 in a one year period. Since the availability of the metal is extremely limited, local catastrophes or disgruntled workers could create extreme market fluctuations in short periods of time.

Platinum is used in significant amounts as compared to its availability. It has been estimated that, if all mining were stopped today, the world’s currently available Platinum supply would be exhausted in one year or less.

Gold-Traders purchases Platinum for cash. View our scrap platinum prices to see our current rates, which are updated on a daily basis.

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June 16th, 2010 No Comments » Miscellaneous |