Integrated Phosphate Ore Upgrading Process
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Solution Overview
Problem
Traditional methods for upgrading low-grade calcareous phosphate ores are energy-intensive, require excessive reagents, and result in low P2O5 recovery and high CO2 emissions, limiting their scalability and economic viability.
Innovation Solution
An integrated process involving the digestion of low-grade calcareous phosphate ore with sulfuric acid or nitric acid, followed by calcination of phosphogypsum to produce lime and sulfur dioxide, capturing CO2, and recycling sulfuric acid, which allows for the production of high-grade phosphate with reduced sulfuric acid consumption and minimized phosphogypsum waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If traditional chemical acid digestion is used to process low-grade phosphate ore, then high P2O5 recovery can be achieved, but excessive digestion acid and lime/limestone amounts are required
Solution Approach 1:
The patent changes the chemical parameters of the digestion process by using nitric acid instead of sulfuric acid, and by controlling the digestion conditions to produce calcium nitrate solution that can be directly evaporated to obtain high-grade phosphate products, thereby reducing the need for excessive lime neutralization
Solution Approach 2:
The patent extracts and utilizes the calcium from the low-grade phosphate ore during digestion, converting it into valuable calcium nitrate fertilizer product, thereby transforming the excessive calcium content from a waste problem into an economic benefit that offsets the acid consumption
2Loss of substance
If thermal processing is used to produce yellow phosphorus or P2O5 vapor, then phosphoric acid can be produced, but the process is energy intensive and requires additional additives
Solution Approach 1:
The patent replaces the thermal/mechanical phosphorus recovery process with a chemical digestion process using nitric acid, which occurs at lower temperatures and directly produces soluble phosphate compounds that can be evaporated to high-grade products, eliminating the need for energy-intensive thermal processing and additional additives like pet-coke
Solution Approach 2:
The patent changes the temperature and chemical parameters of the processing by using aqueous nitric acid digestion at relatively low temperatures followed by evaporation, instead of high-temperature thermal processing, thereby significantly reducing energy consumption
3Productivity
If calcination of low-grade calcareous phosphate ore is performed, then the process is scalable, but P2O5 recovery is low and concentrate reactivity is significantly reduced
Solution Approach 1:
Instead of calcining the ore first and then processing it, the patent inverts the sequence by digesting the low-grade calcareous phosphate ore with nitric acid first, and then evaporating the solution to obtain high-grade phosphate products directly, thereby avoiding the reactivity loss and P2O5 recovery problems associated with calcination
4Quantity of substance
If physical beneficiation processes are applied to upgrade low-grade phosphate ore, then higher concentrated phosphate rock can be produced, but total recovery is less than 65% due to losses at different stages
Solution Approach 1:
The patent extracts P2O5 from low-grade phosphate ore through chemical digestion with nitric acid, converting it into soluble phosphate compounds that can be fully recovered through evaporation, thereby avoiding the P2O5 losses that occur during physical beneficiation stages such as crushing, grinding, and separation
Solution Approach 2:
The patent changes from physical separation parameters to chemical dissolution parameters, using nitric acid digestion to dissolve phosphate minerals and then recovering them through evaporation, which achieves higher recovery rates than physical beneficiation methods
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 process increases P2O5 recovery to 80-90%, reduces CO2 emissions, and enhances the economic viability by utilizing low-grade phosphate reserves previously rejected due to low P2O5 content or high impurity levels, achieving 200-300% of conventional phosphate concentrate capacity with 60-75% less sulfuric acid consumption.
Implementation Method 1
digestion of low-grade calcareous phosphate ore with sulfuric acid or nitric acid
Implementation Method 2
calcination of phosphogypsum to produce lime and sulfur dioxide
Implementation Method 3
capturing CO2
Implementation Method 4
evaporation of the digested solution
Data Source
Figure 1
AI summary
A new integrated method based on upgrading low-grade calcareous phosphate ore with low CO2 emissions and low phosphogypsum waste production. The invention provides an alternative integrated method that increases P2O5 recovery, reduces costs, minimizes the environmental impact of product phosphogypsum and CO2, and overcomes limitations due to different impurities that have negatively affected the yield of traditional processes to a wide range of natural phosphate sources.