Removing heavy metals where it matters most
Heavy metals pose challenges across a number of industries. Their presence can compromise product safety, reduce process efficiency, and create risks for humans, animals and sensitive technologies. Syensqo’s ACCO-PHOS® reagents remove heavy metals in applications where purity is critically important. ACCO-PHOS® is compatible with technical-grade phosphoric acid used for fertilizers and animal feed, with potential applications in purified phosphoric acid (PPA) used for food, pharma, electronics and batteries. In addition to phosphate-related applications, ACCO-PHOS® is being explored for various mineral processing applications to address unique impurity removal challenges.
Heavy metal reduction
ACCO-PHOS® reagents can help customers reduce concentrations of heavy metals such as cadmium and arsenic by more than 90%. Unlike conventional solutions, ACCO-PHOS® also introduces the potential to remove other heavy metals, such as mercury and copper.
Efficient & cost-conscious
ACCO-PHOS® reagents substantially improve operational efficiency by reducing the loss of phosphate and other minerals that normally result from excessive heavy metal concentrations. Additionally, ACCO-PHOS® is a bolt-on technology requiring minimal capital expenditure and no additional unit processes. The product dose can be adjusted based on heavy metal levels in the feed to consistently achieve heavy metal removal targets.
Safety & sustainability
ACCO-PHOS® reagents generate minimal-to-no hydrogen sulfide, thereby reducing the risk of production worker exposure to hazardous chemicals. For this reason — along with its downstream benefits for food safety and ecosystem preservation (such as reducing heavy metal runoff into waterways) — ACCO-PHOS® can play an important role in helping organizations achieve their sustainability goals.
Supply chain flexibility
ACCO-PHOS® enables plants to operate flexibly by allowing them to source ore with varying concentrations of heavy metals.
Compliance and product differentiation
By enabling producers to develop offerings with low heavy metal content, companies across various sectors can unlock greater value through product differentiation and premium brand positioning. As regulations become more stringent and initiatives such as the EU’s Green Label and Safe Food/Feed programs gain momentum, industries are increasingly shifting toward safer, more sustainable solutions. Our innovative heavy metal removal technology was developed in anticipation of these evolving standards, supporting organizations in meeting future requirements and maintaining their license to operate in a rapidly changing landscape.
Removing cadmium, arsenic and other heavy metals from fertilizers and animal feed
Fertilizer and animal feed producers rely on ACCO-PHOS® to help feed the world’s growing population. Phosphate rock used in the production of these products often contains cadmium, arsenic and other heavy metal impurities at concentrations that are considered to be toxic and mutagenic to humans. Accordingly, existing and pending heavy metal regulations, especially in the EU, limit heavy metal content in finished phosphate fertilizers and feeds, necessitating the removal of impurities.
Many decadmiation technologies offer high cadmium removal rates from phosphoric acid, but few have been implemented due to process inefficiencies or undesirable byproducts; as a result, fertilizer producers have been slow to adopt these technologies at industrial scale.
Used primarily in the filtration stage within phosphoric acid plants, ACCO-PHOS® heavy metal removal reagents provide a simple, effective and economical technology for achieving significantly reduced cadmium and arsenic levels in phosphoric acid, enabling compliance with current and anticipated regulatory requirements.
The data shown here summarizes findings from wet phosphoric acid plants using ACCO-PHOS® heavy metal removal reagents for downstream fertilizer and animal feed applications.
Figure: A typical ACCO-PHOS® dose response curve in concentrated phosphoric acids from two different plants is depicted in the chart above. For a cadmium rich acid from plant A, up to 95% of cadmium reduction is achieved at a dosage of 2 kg/t of P2O5. In plant B, significant reduction in both arsenic and cadmium was achieved with a higher dosage of ACCO-PHOS® required due to the significantly higher levels of cadmium present in the phosphoric acid of plant B.
ACCO-PHOS® technology has been proven at an industrial scale with multiple plants consistently purchasing commercial quantities to purify phosphoric acid. The following table provides a list of plants that have or are currently using ACCO-PHOS® at a pilot or industrial scale, with pertinent application information and performance details.
Application Point | ACCO-PHOS® Dose kg/Ton P2O5 | Temp (°C) | Contact Time | Heavy Metal Removed | |
| Plant A | Weak Acid Filter Feed Slurry | 5 - 6 | 72 | 10 seconds | 73% Reduction in Cadmium |
| Plant B | Strong Acid | 2 | 60 | 20 minutes | 91% Reduction in Cadmium |
| Plant C | Strong Acid | 3 | 80 | 2 minutes | 90% Reduction in Cadmium |
| Plant D | Pilot Unit, Strong Acid | 2.5 | 70 | 5 minutes | 97% Reduction in Arsenic |
| Plant E | Pilot Unit, Strong Acid | 5 | 60 | 10 minutes | 83% Reduction in Cadmium |
Beyond phosphate: Heavy metal removal of lead from rare earth elements and from other sources
In addition to phosphate fertilizers and animal feed, ACCO-PHOS® technology shows potential for diverse mining applications and specific impurity removal challenges. For instance, mining operations are exploring whether ACCO-PHOS® can reduce lead levels to improve the efficiency of rare earth separation processes, supporting industries such as electronics, e-mobility and clean tech. Syensqo continues to invest in R&I to advance ACCO-PHOS®, expanding its ability to remove a broader range of heavy metals and impurities from mineral processing feeds. We work closely with customers to develop tailored solutions that achieve heavy metal reduction at viable costs.
White Paper: Removing Heavy Metals from Fertilizers and Animal Feed
In our new white paper, learn about trends and challenges in heavy metal removal along with actionable solutions.
White Paper: Removing Heavy Metals from Fertilizers and Animal Feed
In our new white paper, learn about trends and challenges in heavy metal removal along with actionable solutions.