|Vanadium and Niobium Substitution|
Michael Drozd, Vice President of Operations, Prophecy Development Corp.
Date April 26, 2019
As the vanadium market becomes tighter, the name niobium (also known as columbium) begins to be bandied about. To understand why niobium is under discussion, you will need a little chemistry background. Vanadium is an element with the atomic number of 23 and a molecular weight of 51. It is located on the periodic table just below vanadium, which indicates it shares with it some chemical properties. Niobium has an atomic number of 41 and a molecular weight of 93. So on an atomic basis, niobium is 45.2% heavier than vanadium.
When you talk about elements, you speak in terms of moles. One mole of vanadium is 51 grams, and it contains 6.023X1023 atoms. But a mole of niobium is 93 grams and contains the same number of atoms. This relationship is known as Avogadro’s number. The relationship is immutable and applies always. This gets us back to the statement that niobium is 45.2% heavier than vanadium: an alloy with a certain molar amount of niobium will be heavier than an alloy with the same molar amount of vanadium (other things being equal). This makes a difference when you are trying to improve fuel mileage in airplanes or motor vehicles. (Note: Military grade aluminum from your favorite truck commercial contains no vanadium. Military grade refers to the specifications used by the military to purchase aluminum alloy.) The amount of vanadium in steel and glass (used to color the glass or, in the case of smart glass, as an integral part of the material) comes to less than 0.5% in an automobile. The largest use of vanadium by far is in structural steel.
As the term alloy was used above, what an alloy is must be understood. An alloy is a metallic solid composed of a homogeneous mixture of a metal with at least one other metal, metalloid, or non-metal. Most metals you come in contact with are alloys rather than pure. Common alloys are stainless steels (SS210, SS410, SS304) in cars and appliances, aluminum (series 6000 aluminum, such as 6063) in doors and windows, and structural steel (A-572) in buildings and cars. So it can be said that an alloy is a mixture of metal additives in a metal base (iron, aluminum, nickel, etc.). They are produced because the mixture has properties better suited to the intended use than the metal base.
The addition of vanadium (or niobium) to a rebar (structural steel) recipe makes a stronger metal. The same idea goes for other metal alloy bases. But this alloying of metal not only increases strength, but in some cases it imparts corrosion resistance, abrasion resistance, or an increase or decrease in the potential flow of electricity. Alloy steels are usually a mixture of steel and 1–20% nickel, 1–20% chromium, and minor amounts of manganese, silicon, molybdenum, cerium, vanadium, niobium, aluminum, carbon, and a myriad other metals.
Each of these mixtures has been developed for specific uses, with the ingredient proportions determined by trial and error. The metals are mixed in small batches, and the resulting alloy is tested to determine its properties.
A superalloy is a mixture of metals with a nickel base. These alloys are resistant to corrosion or temperature or both. They are important because they can be used in conditions that would destroy most metals.
In something known as high strength low alloy (HSLA) steel, a minor addition (many times less than 0.5%) results in a large increase in strength. HSLA steels are used in building structures (structural steel), automotive frames, airplane fuselages (aluminum alloys), and jet engines (titanium alloys). All of these alloys use vanadium. There are some uses of alloys (such as rebar, reinforcing bars that are part of concrete structures) that can use the “periodicity” of a metal (elements in the same column of the periodic table sharing chemical and alloying properties) to substitute for the metal above or below it on the periodic table. This is the case for vanadium and niobium, as they are both in column 5B and so have similar properties.
The difference between vanadium HSLA steel and niobium HSLA steel derives from the manufacturing process and the quality control. Vanadium steel can be manufactured at a lower temperature due to better grain size formation. Niobium rebar has to be raised to a higher temperature and be cooled under much more stringent conditions so as to maintain metal quality. Additionally, niobium rebar can be more brittle (cracks form earlier) than vanadium rebar. This means that after proper alloy development, it is possible to substitute one metal for the other. These substitute alloys have slightly different properties, and the particular alloy has to be vetted to determine whether the differences are minor. Usually, as the molecular weight increases, the elements in the group become less viable as a substitute—because the molecules become too large. So niobium HSLA alloys may be more brittle than vanadium alloys, but this brittleness may be acceptable since the tensile strength (the maximum load that a material can support without fracture when stretched, divided by the original cross-section area of the material) may be a more important property than the lateral stability or shear strength. (Shear strength is a material’s ability to resist forces that can cause parts of the internal structure of the material to slide against each other. Adhesives tend to have high shear strengths.)
As the prices of commodities change, substitution is always considered in order to moderate the cost. Under the best conditions, an inexpensive, widely available material is substituted for the expensive material. But under most conditions, the material available for substitution is only slight less expensive. Another factor is that since the substituted item probably has a finite production level, sudden use by another industry can cause price repercussions that may make the substituted material more expense than the original.
In 2018, United States niobium consumption was about 10,000 tonnes, 27% higher than the previous year (2014 usage was 10,000 tonnes). World niobium production is 68,000 tonnes, 88% of which is from a mining complex in Brazil. Another 10% is from at a mine in Canada, and the remaining 2% comes from Africa and Australia. The estimated price for 2018 US consumption was $12.80/lb. The niobium market has been very stable for years, and the increase in US consumption was absorbed by the market. Vanadium production is significantly higher than niobium production (which was 73,000 tonnes worldwide in 2018). If niobium is not available at a reasonable price, the first choice for substitution is tantalum (world production, 1,800 tonnes). But that metal is less suited to HSLA substitution, and its low world production level makes its use as an inexpensive substitute problematic.
One can be sure that any of the metals that can be used as a substitute for vanadium will be explored when the price of vanadium increases. But the lower production levels of these metals and the stability of their supply probably limits their usefulness as substitutes for vanadium. While economics will force substitutions for vanadium, it is expected that the price advantages will be short-lived and that prices will increase since the limited supply and low potential increase in production will dry up metal supply.
Therefore, vanadium substitution will come to the market to the extent possible, and the less desirable properties will be accepted with potential savings. But the available substitute production is limited, and it will probably not cover the expected annual increase in usage (6%, or 4,000 to 5,000 tonnes per year). So until new production comes online, the price of all of these metals will probably experience upward pressure.
Mr. Drozd is the Vice President of Operations at Prophecy Development Corp (TSX: PCY, OTC PRPCF) which is developing America’s first primary vanadium mine. Mr. Drozd specializes in metallurgy with 40 years of experience in the mining industry with firms such as Barrick and AMEC. Mr. Drozd has authored publications in gold flotation, gold processing, heap leach operations, cyanide detoxification, and carbon absorption technology. He also holds patents in molybdenum flotation, cyanide detoxification and vanadium recovery.
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