The distillation of coal for illuminating gas yields ammoniacal liquor, a valuable source of ammonia. This chapter details the extraction and purification processes, including settling tanks to separate tar and the use of Mallet's apparatus for manufacturing ammonium sulfate or caustic ammonia.
Key Takeaways
- Ammoniacal liquor is a byproduct of coal gas production and contains valuable nitrogen compounds.
- Settling tanks are essential for separating tar from ammoniacal liquor before further processing.
- Mallet's apparatus efficiently converts ammoniacal liquor into useful products like ammonium sulfate.
Practical Tips
- Ensure proper settling time to remove tar from gas liquor before distillation.
- Use Mallet’s apparatus for efficient conversion of ammonia into valuable compounds.
- Maintain clean and well-maintained equipment to maximize yield and efficiency.
Warnings & Risks
- Improper separation of tar can lead to environmental complaints and health hazards.
- Inadequate purification of ammoniacal vapours may result in the release of harmful substances.
Modern Application
While modern gas production methods have changed, understanding historical ammonia extraction techniques provides valuable insights into chemical engineering principles. These processes are still relevant for small-scale industrial applications or emergency situations where traditional infrastructure is unavailable.
Frequently Asked Questions
Q: What percentage of nitrogen in coal typically ends up as ammonia?
The text states that the yield of ammonia from coal is far short of the total nitrogen content, with only about 0.21% of the nitrogen in coal being obtained as ammonia in the best works.
Q: How does Mallet's apparatus work to extract ammonia?
Mallet’s apparatus uses a series of boilers and condensers to heat and distill ammoniacal liquor, releasing ammonia which is then condensed and absorbed into sulfuric acid or water to produce ammonium sulfate or caustic ammonia.
Q: Why are settling tanks important in the process?
Settling tanks are crucial for separating tar from ammoniacal liquor before further processing, ensuring that only clear liquid is used which improves efficiency and reduces environmental impact.