Zinc Smelting What role did it play in the Donora disaster?

Zinc Ore

Main Component Zinc sulfate (ZnS) is the main component of zinc ore

The Zinc Smelting Process

Two Smelting Processes Hydrometallurgic & Pyrometallurgic Contrast the two zinc refining processes (2 differences) Which process would be used to smelt zinc ore with lots of lead? Which process is the most used globally?

Step 1: Roasting __ ZnS + __ O 2  __ ZnO + __ S CaF 2 + H 2 SO 4 → CaSO HF What type of reaction is this? (See the choices above)

Step 1: Roasting Byproducts Where does the sulphur go? Sulphur combines with oxygen forming sulphur dioxide which is then converted sulfur trioxide and finally to sulphuric acid. S + O 2 > SO 2 2 SO 2 + O 2 > 2 SO 3 H 2 O + SO 3 > H 2 SO 4 Type of reaction:

Step 1: Roasting Byproducts Important note: During this step, other “waste” compounds are broken down releasing various harmful gases. Example: Fluorspar (CaF 2 ) reacts with sulphuric acid forming calcium sulfate and hydrogen fluoride gas. CaF 2 + H 2 SO 4 > CaSO HF Type of reaction:

Hydrometallurgic Process

Step 2: Leaching Sulphuric acid is added to dissolve zinc oxide forming zinc sulphate and water. Write the chemical equation for this reaction. Prove that it is balanced.

Activity of Metals Circle the MORE reactive element in each pair. Pair 1: Pb Li Pair 2: Ca Ni Pair 3: Mg Mn Li Most Reactive Least Reactive Rb K Ba Sr Ca Na Mg Al Mn Zn Cr Fe Cd Co Ni Sn Pb H2H2 Sb Bi Cu Hg Ag Pt Au

Step 3: Purification Powdered zinc (Zn) is added to the zinc sulphate solution. The zinc (Zn) reacts with copper sulphate (CuSO 4 ) – one of the impurities. Predict how zinc will react based on the activity chart. Write the correct equation here. Identify the type of reaction: Li Most Reactive Least Reactive Rb K Ba Sr Ca Na Mg Al Mn Zn Cr Fe Cd Co Ni Sn Pb H2H2 Sb Bi Cu Hg Ag Pt Au

Step 4: Electrolysis Circle the zinc product. 2 ZnSO H 2 O > 2 H 2 SO Zn + O 2

Pyrometallurgic Process

Step 2: Sintering The zinc oxide is sintered where carbon in combustion gases reacts with impurities such as lead oxide, cadmium oxide and fluorine… CO 2 + PbO > PbCO 3 CO 2 + CdO > CdCO 3 CO 2 + 4F > CF 4 + O 2

Step 3: Retorting Balance this equation. __ C + __ O 2 > __ CO Fill in the missing compounds. ZnO + ____ > Zn (vapor) + ____