Back to Basics: Claims of Mineral Processing Patents and Infringement

When people think of patents it is typically with reference to physical products or apparatus as this provides an easy way in which to visualise the patented invention. Processes (or methods) can similarly be patented and such patents are used extensively in the mining industry to protect new mineral processing technologies. But without a physical product to provide a reference, it can often be difficult to visualise the scope of these patents.

Patent Specification Background

A patent is split into two main parts, the description and the claims.

The description provides a discussion of the technology, often with reference to the problems addressed by the patented invention. The description also provides a detailed explanation of the various features of the technology and preferred ways in which the invention may be produced and/ or implemented.

The claims reduce the technology to its essential features and are used to define the scope of the patent. Claim 1 (and other independent claims) will typically define the broadest scope of the invention and the dependent claims introduce further important features. Claims are typically described with reference to a set of features, these are often referred to as the claim integers. Where the invention relates to a product/ apparatus, the claims will describe a set of physical features of the product. Where the invention relates to a process, the claims will describe a set of process steps. Once granted, the claims will be used to determine infringement of the patent.

To put this into perspective, Claim 1 for a theoretical hydrometallurgical process may be granted as follows:

A hydrometallurgical process for extracting metals from an ore, comprising the steps of:

. subjecting the ore to a size reduction step to produce a feed stream with an average particle size of about 500 μm
b. subjecting the feed stream to a sulphuric acid leach at a temperature of at least 50°C
c. separating undissolved solids from the product of the leach step
d. recovering a metal hydroxide solid from the leach solution by adding a hydroxide source.

The scope of such a patent is defined by particular steps (a)-(d).


Patent infringement occurs when an alleged infringer has exploited a product or process which falls within the scope of one or more claims of a granted patent without the authorisation of the patent owner. In order for this to occur, the infringing product must include all essential features of one or more claims, or the infringing process must include all of the essential claimed steps. In the above example, if we agree all the steps are essential, any third-party process that includes all of steps (a)-(d) would infringe this patent, irrespective of any other steps that are also included in the third party’s process. On the other hand, if the third-party process did not include all of these features as set out in Claim 1, it would not infringe the patent.

It’s All in the Words

Given the importance of the claim language in the determination of patent infringement, it is important that the language used in the claims is sufficiently broad. It is also important to ensure that the integers in the claim are in fact essential, as this prevents third parties from easily replacing one or more features of the claimed process in order to avoid infringement. The main difficulty faced when claiming mineral processes is that many different processing routes are often available at each step in a process, so care needs to be taken to ensure all obvious variations are covered. This can be difficult when the focus is often on the flowsheet that is to be commercially implemented. Taking the above example, a third party could potentially avoid infringement by ensuring their own process including one or more of the following:

  • Crushing ore to a different average particle size
  • Conducting the leach using a different acid or at ambient temperature
  • Recovering the metals by solvent extraction or precipitating a carbonate instead of a hydroxide

The options available to third parties can be limited by ensuring that the language used in the claim is broad enough to cover alternatives.

It’s All in the Words

When applying for a patent, care must be taken to ensure that the patented claims describe the invention in a manner that is sufficiently broad to cover not only the particular product/process that is intended to be implemented commercially but also alternative variations that third parties may look to implement.

When considering whether your own product/process would infringe another patent it is important to carefully review the granted claims to evaluate whether your product/process does, in fact, include all of the essential features of the claim. It may also be possible to avoid infringement by replacing one or more of the claimed features without departing too far from your intended path.

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