Lesson-specific diagram for Smelting and pulp-and-paper chemistry as process systems. It visualizes the reasoning sequence tied to $\text{mass/energy balance}+\text{emissions/control}$. Text alternative: Industrial chemistry can be compared using reaction chemistry, feedstocks, energy use, product recovery, emissions, and treatment systems. Choose a representation that matches the chemical scale and evidence; do not infer more precision or mechanism than the data support.