The Flame Retarding and Smoke Suppression of Flexible PVC
The purpose of this paper is to present an overview of the various technologies used to flame retard and smoke suppress PVC. It gives guidelines on how to formulate PVC using these additives and also discusses the effects these additives have on the physical properties, heat stability and processibility of PVC compounds using them. It is impossible to discuss every aspect of the flame retarding and smoke suppressing of PVC in a paper designed to be presented in a 30-minute talk. However, this paper offers both beginning and experienced formulators useful information in this area.
Flame retardants and smoke suppressants for flexible vinyl compounds
This paper reviews a number of technologies employed to reduce flammability and suppress smoke in flexible vinyl compounds. Advantages and disadvantages of the various systems are discussed, along with postulated mechanisms of action. Typical applications, approximate market prices, and major suppliers are also listed.
Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.