UT (Tax & Chancery) UT/2023/000101 - [2025] UKUT 00072 (TCC)

The FTT heard evidence from a general manager of FCC and from two expert witnesses. It made extensive findings of fact but for present purposes we set out the material facts relatively briefly in the following paragraphs. There was no issue about the FTT’s findings and we take the facts largely from a helpful summary in the appellants’ skeleton argument.

Singleton Birch is the operator of a landfill site at Camp Wood in Lincolnshire. FCC is a waste management company with a site at Knostrop in Yorkshire at which it treats hazardous and non-hazardous wastes.

Cristal Pigment UK Limited (“Cristal”) is a manufacturer of titanium dioxide pigment at its works in Stallingborough in Lincolnshire. Cristal extracts titanium dioxide pigment from ores. The pigment is used in a range of industrial and consumer products. The manufacture of titanium dioxide pigment produces a waste which is an acidic ferrous chloride solution. The ferrous chloride waste is hazardous due to its acid content, the presence of heavy metals and naturally occurring radiation. It must be treated before disposal in landfill.

Cristal has its own on-site dedicated treatment facility at which it treats some of the ferrous chloride waste. The ferrous chloride waste also contains many other components derived from the titanium dioxide manufacturing process including chlorides, sulphates, heavy metals such as iron, titanium, aluminium, magnesium and silica. These components vary in concentration due to raw material and process variations. Cristal is unable to treat all the ferrous chloride at this facility.

Cristal treats the ferrous chloride waste with a chemical reagent containing calcium hydroxide. This reagent is sometimes referred to as slaked lime. Slaked lime in powder form is 90% calcium hydroxide. The remaining 10% is other alkaline metal compounds which would react with ferrous chloride. The powder is mixed with water from Cristal’s site to form a slaked lime slurry which typically has a calcium content of 10-20%. Calcium hydroxide is a hazardous material due to its alkalinity. The alkalinity of the calcium hydroxide in the slurry reacts with the acidic ferrous chloride waste, resulting in the production of a non-hazardous calcium based reaction waste.

This waste is then de-watered and compacted into a solid form known as filter cake, which is a non-hazardous waste (“the Cristal Waste”). The filter cake still includes some water which, together with dissolved contaminants, amounts to 40 – 50% of the filter cake by weight. The Cristal Waste therefore does not consist entirely of reacted calcium compounds.

The Cristal Waste is transported to Singleton Birch’s Camp Wood site where it is disposed of by way of landfill. The site was created by the extraction of calcium carbonate for slaked lime production, and is now operated so as to fill the void resulting from this extraction.

HMRC accept that the disposal of the Cristal Waste at Camp Wood attracts the lower rate of landfill tax because the Cristal Waste is entirely a calcium based reaction waste from titanium dioxide production.

Cristal does not treat all of the ferrous chloride waste at its on-site treatment facility in Stallingborough. Some is transported to FCC’s Knostrop site by road tankers, where it is transferred into two storage tanks. From there it is transferred to mixers, where it is mixed with the solid APCR.

APCR is itself a waste, produced by energy from waste facilities such as incinerators. The process of incinerating waste releases acid gases, heavy metals and toxic persistent organic pollutants. Slaked lime is injected into the incinerator flue to neutralise the acid gases. The gases are then passed through bag filters which capture the solid residues. The amount of slaked lime injected into the incinerator is greater than the amount strictly required to neutralise the acid gases. This is to ensure excess alkalinity is always present and that the acid gases are removed to the extent required by the facilities’ operating permits. The solid residues are therefore alkaline because they contain unreacted calcium hydroxide from the slaked lime. The solid residues are removed and constitute the APCR. APCR contains a mix including unused calcium hydroxide, other reactive alkaline compounds and some non-calcium reactive compounds. Its composition depends in part on what waste was incinerated. The calcium based reactive compounds comprise a significant majority of the reactive compounds in the APCR and tend to be more reactive than the non-calcium compounds. The APCR is sufficiently alkaline to be classed as hazardous.

When the APCR is mixed with the ferrous chloride, the alkaline calcium hydroxide in the APCR reacts with the ferrous chloride to neutralise the acid. The usual range of reactivity of the APCRs is 10 – 30%. The resulting FCC Waste is non-hazardous. It is transported to Singleton Birch’s Camp Wood site where it is disposed of in landfill along with the Cristal Waste.

The site permits at Knostrop and Stallingborough required the operator to take appropriate measures to ensure that raw materials are used efficiently and consider whether suitable alternative materials could reduce environmental impact, improve the efficiency of raw material use and take appropriate measures to ensure that waste produced is recovered.

It was common ground that the reactions giving rise to the FCC Waste were primarily between calcium compounds in the APCR and the ferrous chloride. A significant part, at least 70%, of the material comprising the APCR did not react with the ferrous chloride. Most of the reactive material in the APCR (more than 50%, if not more) was calcium based. The FTT also found as a fact at [136] and [138] that a calcium based reaction did occur in the process which produced the FCC Waste. At [122] it found that between 57% and 72% of the FCC Waste consisted of material which was not the result of a calcium based reaction. To a very significant extent the FCC Waste consisted of elements which were part of the APCR and which did not react with the ferrous chloride.

Some 3.9 tonnes of APCR are required to neutralise 1 tonne of ferrous chloride. In contrast, some 260kg of slaked lime powder would be required to neutralise the same amount of ferrous chloride.

Camp Wood can only accept a restricted range of waste, specifically precluding active waste or hazardous waste. The operating permit issued to the site and regulated by the Environment Agency reflects this. It provides for 5 years of caretaking following closure of the site, rather than the 60 years required for landfill sites which accept active waste or hazardous waste.