Sulphate Removal Effluent Treatment Process
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Solution Overview
Problem
The SAVMIN process for treating mine waters is characterized by a large number of solid/liquid separation steps, which complicates the process and increases costs.
Innovation Solution
Combining heavy metal hydroxides and gypsum precipitation in a single unit operation, reducing the number of reactors and solid-liquid separation units, and using a single solid-solid separation unit for amorphous aluminium trihydroxide and gypsum, thereby simplifying the process and lowering costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate precipitation and separation steps are used in the SAVMIN process, then removal efficiency of sulphate and calcium is improved, but process complexity and capital costs increase due to multiple unit operations
Solution Approach 1:
The patent combines multiple precipitation steps (heavy metal hydroxide precipitation and gypsum precipitation) into a single reactor unit, and combines multiple solid-liquid separation steps into a single separation unit. This merging of operations maintains removal efficiency while reducing process complexity and capital costs by eliminating the need for multiple separate reactors and separation units
2Manufacturing precision
If multiple solid-liquid separation units are used, then separation precision is improved, but operating costs and process complexity increase
Solution Approach 1:
The patent consolidates multiple solid-liquid separation operations into a single separation unit that handles all solid removal in one step. This approach maintains the required separation precision for removing heavy metal hydroxides, gypsum, and ettringite while significantly reducing operating costs and simplifying process operation by eliminating multiple separation units
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This modification reduces capital and operating expenses, enhances recovery efficiency of amorphous aluminium trihydroxide, and minimizes co-precipitation of basic aluminium sulphate, resulting in a more efficient and cost-effective treatment process.
Implementation Method 1
raising the pH of the acid waste water so that heavy metals precipitate out of solution in the form of hydroxides
Implementation Method 2
the supersaturated solution is de-supersaturated by using gypsum seed to remove the calcium sulphate as gypsum
Implementation Method 3
remove the calcium sulphate as gypsum in a high solid precipitator
Implementation Method 4
The amorphous aluminium trihydroxide is then separated from the second supersaturated solution following the removal of the supersaturated calcium sulphate solution by de-supersaturating the latter by removing calcium sulphate as gypsum
Data Source
AI summary
Disclosed is an acid waste water treatment and method wherein heavy metal hydroxides and gypsum are precipitated in a single operation and wherein amorphous aluminium trihydroxide and gypsum are separated in a single solid-solid separation unit.