Cleaning Up the Waste: Federal Court Invalidates Patent for Treating Waste Material from Mining Operations

On August 24, 2015, Justice Phelan held that Canadian Patent No. 2,515,581 is invalid for obviousness (2015 FC 997). This action involved only a challenge to the validity of the 581 Patent by SNF as CIBA’s counterclaim for infringement was settled during the course of the trial.

The 581 Patent is generally directed to a method of treating slurries from mineral processing operations that are often deposited on land where the solid particles separate from the water leaving clean water and rigidified solid material that can be used to rehabilitate or reclaim land. The more solid particles removed, the cleaner the water. One method of removing fine particles is the addition of a polymer that co-absorbs on multiple particles creating an aggregate that is more easily removed than the individual particles.

The method taught by the 581 Patent involves adding a water soluble polymer in solution to the waste material to achieve the desired rigidity. Justice Phelan noted that in many ways, the method of the 581 Patent consisted of adding enough water soluble polymer until one achieved the desired result. SNF argued that the 581 Patent was invalid based on anticipation by prior art and prior use, obviousness, insufficient disclosure, overbreadth and for containing false and misleading statements.

Claims Construction

Justice Phelan’s construction of the claims largely focused on determining the meaning of the claim term “rigidification” or “to rigidify” which Justice Phelan found to mean increasing the yield stress of a mineral deposit rapidly whereby the flow of the deposit is minimized and the weight of subsequent layers of like deposits is supported.


A piece of prior art, the “Gallagher Patent” disclosed a process where rigidification is achieved by introducing solid particles of a water soluble polymer into the suspension as opposed to the 581 Patent which achieves rigidification by addition of a water soluble polymer in solution. Justice Phelan noted that the objectives, language and invention of the Gallagher Patent are almost identical to the 581 Patent and the key issue was whether the Gallagher Patent disclosed and enabled the use of a water soluble polymer in solution to achieve rigidification or whether it is limited to using solid particles of a water soluble polymer.

While acknowledging that the Gallagher Patent recognizes that solution addition is an alternative form of treatment, Justice Phelan held that the Gallagher claims specifically disclose dry particle addition of the polymer to achieve the desired rigidification. Even if the Gallagher Patent disclosed the subject matter of the 581 Patent, that disclosure is not enabling:

[170] … The experts agreed that the form of addition is integral to the process followed and this is relevant as enablement for particle addition does not equate to enablement for solution addition due to their different characteristics. Thus, by teaching particle addition and providing a process to its application, Gallagher does not enable solution addition without meaningful experimentation.

Justice Phelan also found that the evidence supporting the alleged prior uses was not reliable, lacked accuracy and could not be corroborated. As such, it was incapable of establishing anticipation


Although not anticipatory, Justice Phelan held that the substitution a solution of a water soluble polymer would have been obvious to in light of the common general knowledge of flocculation. In coming to this conclusion, Justice Phelan rejected Ciba’s arguments focused on the impact of the optimum dosage of the water soluble polymer since the optimum dose was not claimed or raised in the Patent.

A copy of Justice Phelan’s Reasons for Judgment can be found here.