Tight Sulfur Supply Drives Up Yellow Phosphorus Market Price Through Downstream Substitution Demand

Tight Sulfur Supply Drives Up Yellow Phosphorus Market Price Through Downstream Substitution Demand

[Introduction]
The yellow phosphorus market has recently seen a strong price rally, starting from tight domestic sulfur supply. Looking ahead to next week, the sulfur market is expected to continue fluctuating at high levels amid a standoff between industrial and trading participants. The tight sulfur supply is affecting the supply pattern of wet-process phosphoric acid, and through the substitution relationship, it boosts demand for thermal-process phosphoric acid. The logic that this benefits yellow phosphorus prices remains in place.

As of May 2026, global sulfur inventories are at multi-year lows. Geopolitical conflicts continue in the Middle East, a major producing region, with damaged facilities and disrupted shipping. Inventory at major Chinese ports stands at only 1.0262 million tonnes, less than one month's domestic consumption. Sulfur supply is tight. Taking granular product prices at Zhenjiang Port as an example, cumulative price increases since the beginning of the year have reached 80.98%.

During the current cycle, a major yellow phosphorus producer reduced or halted production at its wet‑process phosphoric acid plant due to sulfur shortages, and its guidance price for yellow phosphorus was further raised to 35,000 RMB/ton.

The process substitution logic has been activated, leading to passive growth in yellow phosphorus demand. Wet‑process phosphoric acid relies on sulfur as a key raw material; sulfur shortages have forced production cuts or shutdowns. Thermal‑process phosphoric acid, in contrast, uses yellow phosphorus as raw material. Moreover, the two processes produce phosphoric acid that is substitutable in industrial and new energy applications. As wet‑process phosphoric acid supply contracts, market demand for thermal‑process phosphoric acid increases, thereby pulling up yellow phosphorus demand.

Before this news, some yellow phosphorus producers intended to push market prices to 32,000 RMB/ton. Although downstream market prices followed the increase, the momentum was weak and transactions were sluggish. Market intelligence suggests that downstream buyers' actual acceptable price range for yellow phosphorus was 30,000–30,500 RMB/ton. Therefore, after the market price was pushed to 31,200 RMB/ton, the center of gravity fell back to 30,500 RMB/ton.

After this news was released, the yellow phosphorus market price jumped by 1,500 RMB/ton in a single day to 32,000 RMB/ton. Guidance prices from various producers all showed a strong tone. Intermediaries, optimistic about the future, began replenishing stocks, and actively moved goods at 32,500 RMB/ton and higher. After the market price moved up, some yellow phosphorus producers secured orders at 32,500–32,600 RMB/ton, and subsequently focused on shipment execution. Phosphoric acid, as the main downstream product of yellow phosphorus, also saw its market price rise by about 1,000 RMB/ton last week.

In summary, the recent strong rally in the yellow phosphorus market originated from tight domestic sulfur supply. Looking ahead for sulfur, although tensions in the Middle East have eased, uncertainty remains regarding the full resumption of shipping through key straits. Import vessel arrivals in June are still limited, and port inventories are expected to decline further. Next week, the sulfur market is likely to continue high‑level volatile consolidation amid a tug‑of‑war between industrial and trading participants.

Therefore, the factors linking tight sulfur supply to the wet‑process phosphoric acid supply pattern, and through the substitution relationship to increased demand for thermal‑process phosphoric acid, remain in place. This logic continues to benefit yellow phosphorus market conditions. Going forward, it cannot be ruled out that this factor will further support yellow phosphorus market strength and price expectations.

Impact analysis of continued yellow phosphorus price increases on downstream flame retardant prices

Yellow phosphorus, as the core raw material of the phosphorous chemical industry chain, has seen its price rise from approximately 27,500 RMB/ton earlier to 32,460 RMB/ton this week – an increase of more than 18%. The guidance price from major producers has reached 35,000 RMB/ton. This round of price increases will directly drive up production costs for the following phosphorus‑based flame retardants:

• Red phosphorus flame retardant: Red phosphorus is directly processed from yellow phosphorus, so the cost pass‑through is the most direct. For every 1,000 RMB/ton increase in yellow phosphorus, red phosphorus production costs rise by approximately 1,500–2,000 RMB/ton. It is expected that prices of red phosphorus masterbatch and encapsulated red phosphorus flame retardant will soon follow the increase, and supply may tighten.

• Ammonium polyphosphate (APP): APP uses phosphoric acid or phosphorus pentoxide as raw materials, and phosphoric acid prices have already risen sharply with yellow phosphorus (thermal‑process phosphoric acid up 6.5% week‑on‑week). APP costs are expected to increase by 10–15%, and some producers have already stopped accepting low‑priced orders.

• Melamine phosphate (MP): Raw material costs for both phosphoric acid and melamine are rising, putting clear cost pressure on MP. However, melamine prices have recently fallen due to weak demand (as noted in a previous weekly report), which partly offsets the phosphoric acid increase. Consequently, MP price increases may be relatively moderate.

• Organophosphorus flame retardants (e.g., ADP, DOPO, BDP): These products use phosphorus oxychloride, phenol, etc. as raw materials. Phosphorus oxychloride has already risen about 4% this week. The yellow phosphorus increase will progressively transmit to higher‑end flame retardants such as hypophosphites and alkylphosphinates. It is expected that over the next 1–2 months, quotes for organophosphorus flame retardants will increase by 8–12%.

• Other phosphate flame retardants (e.g., phosphate esters, triphenyl phosphate): These also face rising costs for raw materials such as phosphoric acid and phosphorus oxychloride, and will be forced to follow price increases.

  
  

Overall assessment: In the short term, high‑level volatility in yellow phosphorus will keep cost support strong for phosphorus‑based flame retardants. Combined with summer maintenance at some plants, supply may tighten, making it easy for flame retardant prices to rise but difficult to fall. However, downstream industries such as modified plastics, cables, and sheets have limited ability to accept high prices. The magnitude of flame retardant price increases may lag behind that of raw materials. Some companies may respond by adjusting formulations (reducing phosphorus content or substituting inorganic flame retardants). Downstream users are advised to moderately extend their procurement cycles while paying attention to halogen‑free synergistic formulations to control costs.