Industrial waste going to landfill at R$ 180/ton (roughly USD 35). In the same region, a cement plant buying RDF at R$ 120/ton.
In 2023, Brazilian cement plants co-processed 3.25 million tons of waste as alternative fuel — the highest volume ever, according to the Brazilian Portland Cement Association — and today demand exceeds the supply of qualified material. In this article, we analyze the technical requirements that separate a rejected waste from an accepted fuel: calorific value, particle size, moisture content, and documentation. The goal is to give industrial waste generators the concrete data they need to evaluate whether the material currently going to landfill has the potential to become revenue.
What the clinker kiln demands from fuel
A cement plant’s rotary kiln operates above 850 °C in continuous regime. Any variation in energy input compromises clinker formation. That’s why the cement plant doesn’t accept raw waste. It accepts RDF (refuse-derived fuel) within strict technical specifications.
The central parameter is NCV — net calorific value. NCV measures the useful energy released during combustion, after deducting the energy lost to water evaporation in the material. NBR 16849:2020 (Brazilian standard) classifies RDF into 5 classes by NCV. Class 3 (15-20 MJ/kg) is the minimum for co-processing. Below that, the cement plant rejects the lot because the delivered energy doesn’t offset the logistical and operational cost of feeding the kiln.
In practice, the range cement plants seek most is between 15 and 25 MJ/kg. Mixed plastics deliver 25-35 MJ/kg. Dry wood falls between 14 and 18 MJ/kg. Synthetic textiles reach 20 MJ/kg. When the generator mixes these streams without control, the NCV fluctuates between lots and the cement plant loses kiln predictability.
Moisture is the factor that drives NCV down the most. Material with more than 20% moisture loses useful energy evaporating water instead of generating heat. A batch of plastic scraps that would come in at 28 MJ/kg dry drops to 18 MJ/kg at 25% moisture. On rainy days, material stored uncovered can fall below the acceptance threshold.
Particle size: the kiln has a small mouth
The cement plant specifies maximum particle size in the facility’s environmental permit, typically below 50 mm. Larger material doesn’t burn completely within the kiln’s residence time. Pieces above 80 mm can obstruct the feed system.
Producing RDF from industrial waste requires at least two shredding stages. The pre-shredder (equipment such as the PR4000 or PR5000, dual-shaft, low-speed) reduces raw material to around 150 mm and handles metallic contaminants without jamming. Next, the granulator shredder (Q Series, single-shaft, high-speed with internal screen) takes it from 150 mm down to the final range of 30-50 mm. A classifying screen at the output separates material already within spec from what needs to return to the granulator.
This two-stage process ensures uniform particle size and prevents rejection at the cement plant’s intake scale. Out-of-spec material goes back on the truck. No second chances.
The commercial chain has technical requirements
Having material with adequate NCV and particle size solves half the problem. The other half is logistics and documentation.
Minimum volume typically starts at 500 tons/month. The cement plant replaces fossil fuel on a continuous basis and needs regularity. A supplier who shows up “when there’s availability” doesn’t get a contract. The kiln doesn’t stop to wait for a load.
Each delivery requires a waste transport manifest issued through the Sinir system (Brazil’s national waste tracking system), an invoice with the correct waste code, and a lot characterization report (NCV, moisture, composition, chlorine and heavy metal content). Without these documents, the cement plant can’t register receipt with Ibama (Brazil’s environmental agency). And without registration, it won’t accept the material.
The co-processing contract between supplier and cement plant defines the acceptable NCV range, maximum particle size, delivery frequency, and penalties for specification deviations. It’s a technical contract, not just a commercial one.
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The starting point is technical, not bureaucratic
Companies that have never supplied a cement plant usually start by selling waste to an environmental services firm that already has a contract and a structured process in place. The firm handles sorting, shredding, and documentation. The generator stops paying for landfill. As volume grows and justifies structuring the operation internally, the next step is sizing a proprietary processing line.
Jaguar Industrial sizes RDF shredding and classification lines for companies that want to operate directly. The starting point is a composition and NCV analysis of the waste. The result defines whether the material qualifies, its value range, and which equipment meets the particle size required by the destination cement plant.
Before renewing the landfill contract, it’s worth knowing how much the material leaving on the truck is actually worth.