Safety

Product

Environmental Safety of Vecor Tiles

By Dr. Erik Severin,

Director of Technology, Vecor Limited

Vecor has performed extensive testing on tiles made with components derived from coal ash to ensure that no personal, or  environmental, damage is due to these products. Representative tiles made with over 75% recycled content were submitted to the testing lab “ALS Australia” for evaluation and leach testing. ALS is one of the world’s largest and most diversified testing services labs specializing in environmental and industrial health-and-safety testing. Testing was undertaken to ensure that Vecor’s tiles would not leach any metals or minerals - either during their usefullife, or after the structures in which they were installed were demolished.
 
Vecor provide to ALS representative tiles for leach testing. The tiles were vitrified tiles that contained 75% recycled material derived from coal ash(e.g. aluminum silicates). These samples represented Vecor’s standard product line with no special selection process. All sample preparation and testing procedures were performed by ALS staff, independent from Vecor. Some of the tiles were tested whole, and others were crushed into powder by ALS to represent tile dust coming from demolished buildings, and to expose a larger surface area to the leachate.
 
In these tests whole and crushed tiles were both soaked in distilled water, and also separately in slightly acidic water (pH 5 - similar to acid rain),the leachate in each case was filtered, and then analyzed by ICP spectroscopy. ICP is an industry standard analytical technique that can detect metals in the leachate at parts per billion (ppb) levels and is the standard analytical method used by environmental and industrial health labs around the world.
 
There are eight metals that are of concern to most environmental protection agencies and which they regulate. These are listed below in Table 1, along with their allowable limits (according to the USA Environmental Protection Agency). All of our samples were below the limit allowed by the regulations. In fact, in all but one case, the samples were also below the limit of detection of the test equipment. It can be said, without any doubt, that these materials will not leach contaminates into the environment.

Table 1

USA EPA regulated metals with their concentration limits

Arsenic 5 mg/L(ppm)
Barium 100 mg/L
Cadmium 1 mg/L
Chromium 5 mg/L

 

Lead 5 mg/L
Mercury 0.2 mg/L
Selenium 1 mg/L
Silver 5 mg/L

 

Additional metals were investigated to ensure that nothing else leaches from our materials.  The whole list of metals tested is shown in Table 2, along with the detection limits for each metal for the ICP spectroscopic equipment used.

Table 2

Additional metals tested, with the limit of detection by ICP.

Aluminum 0.1 mg/L
Antimony 0.1 mg/L
Arsenic 0.1 mg/L
Barium* 0.1 mg/L
Beryllium 0.05 mg/L
Boron 0.1 mg/L
Cadmium 0.05 mg/L
Cobalt 0.1 mg/L
Iron 0.1 mg/L
Lead 0.1 mg/L

 

Manganese 0.1 mg/L
Molybdenum 0.1 mg/L
Selenium 0.05 mg/L
Silver 0.1 mg/L
Strontium 0.1 mg/L
Thallium 0.05 mg/L
Tin 0.1 mg/L
Vanadium 0.1 mg/L
Zinc 0.1 mg/L

 

 

 

*Barium’s test result was 0.3 mg/L (300 ppb) which was greater than the ICP limit-of-detection, but still well below the allowed limit by the EPA, which is 100 mg/L (100 ppm).  See Table 1 for reference.

The leaching tests showed essentially no leaching – either for the whole tiles or for the crushed tile powder.  This is because the material is sintered (i.e. fused) at over 1200˚C which forms a glass matrix throughout the tile.  During the sintering process the metals are locked into a glassy matrix of aluminum silicates.   They cannot be leached from the glass at standard pH levels and temperatures.   The analytical tests probed regular water leaching (using distilled water - which would have a higher propensity to extract metals) and leaching with slightly acid water (representing acid rain).  Neither of these leachates is active enough to corrode the glassy sheath sequestering these metals, so no metals leached out.  
 
Sequestering metals and minerals in glass is an established, and proven, way to isolate contaminates.  In fact, this is the same method used to ensure that radioactive materials from spent fuel rods from nuclear reactors are secured so that they do not leach if their storage facilities are ever compromised.  There is much literature supporting the effectiveness of this technique.  The same firing procedures used to form vitrified tiles (comparable to any Gris Italian Porcelain) simultaneously sequesters any possible contamination and locks it away into the glassy matrix.