SMM's September 24 sulphuric acid weekly review put China's copper smelting acid index at 1,247.5 yuan per metric tonne, down 103.5 yuan or 7.7 percent week on week from 1,351 yuan.
The print marks a twelfth consecutive weekly pullback in the smelter acid index as the sub-thousand yuan wave spreads from coastal markets into central China, per SMM's headline framing on policy waits and winter stockpiling.
The same survey listed sulfur EXW Shandong at 7,267 to 7,750 yuan per metric tonne, averaging 7,508.5 yuan, up 55 yuan or 0.74 percent week on week, a modest lift in elemental offers alongside weaker acid.
Asian sulphuric acid FOB South Korea was quoted $280 to $320 per tonne, FOB India $300 to $350, and CFR Indonesia $305 to $325 in the published weekly bands.
Shengyishe held the September 24 national sulfur benchmark unchanged at 7,752.33 yuan per metric tonne after three daily gains, a flat elemental line that contrasts with falling smelter acid on the downstream chain.
Shengyishe's September 24 trend screen flipped to counter-rally with a bearish bias as the five-day mean difference eased to positive 42.00 yuan from positive 58.66 yuan on September 23.
Open wires on September 23 put monitored Chinese port sulfur stocks at 940,200 metric tonnes, ample coastal supply that can keep acid and elemental markets from tightening in sync.
Fertilizer Daily's September 20 phosphate review still showed East China liquid sulphur near 7,325 yuan and Zhenjiang granular near 7,150 yuan, coastal fertilizer-chain offers below both the national benchmark and SMM's Shandong EXW average.
BC Insight's September 19 Price Trends kept North American FOB sulphur steady at 1,100 to 1,200 dollars per tonne, the Pacific offer band Alberta recovered sulfur still references when Chinese acid weakens but elemental spot holds.
Alberta Energy Regulator ST3 data run 27 August 2026 put province-wide closing inventory at 11,109,610.9 tonnes for July 2026, the verified_public block stock anchor when Pacific exporters watch Chinese downstream demand.
The Vancouver Fraser Port Authority reported 3,507,428 metric tonnes of sulfur exports in 2025, up 5 percent year on year, showing the Pacific stem can still clear Alberta tonnes when CFR netbacks clear freight.
SMM's August customs put China sulfur imports down 65 percent year on year at 272,323 metric tonnes, weak import demand that can leave domestic plants and smelters competing for limited coastal buying interest.
Desk read: SMM's 1,247.5 yuan smelter acid index is the material downstream move on September 24. Pair it with Shandong sulfur EXW at 7,508.5 yuan and the flat 7,752.33 yuan Shengyishe benchmark when judging whether acid weakness pulls elemental spot lower.