Frequent anomalies often occur in flotation operations. The causes of these phenomena are also complex and often not entirely due to one factor. For the convenience of reference, various common anomalies, causes and adjustment methods are listed. See Table 1. Table 1 Abnormal phenomena commonly found in flotation operations, causes and main adjustment methods
| Anomalies | cause | Main adjustment method |
| Low concentrate grade | 1. Mineral composition and ore oxidation, muddy degree change 2. Concentrate operation mass fraction, large concentrate output 3. Inflatable excess 4. Overdose, reduced selectivity 5. Concentrate scraping | 1. Pharmacy, process 2. Reduce the mass fraction, reduce the amount of output 3. Reduce the amount of aeration 4. Reduce the amount of the agent 5. Reduce the amount of scraping |
| Low recovery | 1. Mineral composition and ore oxidation, muddy degree change 2. Grinding fineness 3. Improper dosage 4. Production overload, flotation time less than 5. Middle mine circulation increased, unstable flotation process | 1. Pharmacy, process 2. Improve the fineness of grinding grade 3. Adjust the agent 4. Reduce the amount of ore given 5. Reduce the amount of foam sprayed |
| Slurry overflow | 1. Flotation quality score is small 2. Grader overflow increases 3. Flotation machine accident, slurry circulation is not good 4. Foaming agent excess 5. Pulp gate is too high 6. Return amount (middle mine) increase | 1. Reduce the amount of water supply 2. Adjust the grinding and grading operation 3. Repair the flotation machine or clean the pipeline 4. Reduce or stop the drug 5. Adjust the gate 6. Reduce the amount of medium ore |
| Pulp surface drop | 1. Flotation mass fraction becomes larger 2. Flotation granularity is coarse 3. Flotation machine's stirring force decreases, gas tube is blocked or shedding 4. The ore grade increases 5. The amount of foaming agent is less than 6. Motor, pipeline, pump accident, Less pulp | 1. Reduce the amount of or increase the amount of water 2. Adjust the grinding and classification operation 3. Repair the flotation machine 4. Add the medicine 5. Increase the amount 6. Repair, clear |
| Foamy sticky | 1. The ore in the ore increases 2. The pH value of the pulp rises 3. The foaming agent is excessive 4. The lubricating oil is mixed in the slurry 5. The drug station accident 6. The amount of scraping is too large for each operation | 1. Adjust the agent 2. Reduce the amount of the regulator 3. Reduce the dosage 4. Add or stop adding the pine oil and analyze the cause 5. Check the dosage of the agent 6. Reduce the amount of scraping |
"Gravity Die Casting. A permanent mould casting process, where the molten metal is poured from a vessle of ladle into the mould, and cavity fills with no force other than gravity, in a similar manner to the production of sand castings, although filling cn be controlled by tilting the die."
Gravity Die Casting
Sometimes referred to as Permanent Mould, GDC is a repeatable casting process used for non-ferrous alloy parts, typically aluminium, Zinc and Copper Base alloys.
The process differs from HPDC in that Gravity- rather than high pressure- is used to fill the mould with the liquid alloy.
GDC is suited to medium to high volumes products and typically parts are of a heavier sections than HPDC, but thinner sections than sand casting.
There are three key stages in the process.
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The heated mould [Die or Tool] is coated with a die release agent. The release agent spray also has a secondary function in that it aids cooling of the mould face after the previous part has been removed from the die.
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Molten metal is poured into channels in the tool to allow the material to fill all the extremities of the mould cavity. The metal is either hand poured using steel ladles or dosed using mechanical methods. Typically, there is a mould [down sprue" that allows the alloy to enter the mould cavity from the lower part of the die, reducing the formation of turbulence and subsequent porosity and inclusions in the finished part.
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Once the part has cooled sufficiently, the die is opened, either manually or utilising mechanical methods.
Advantages
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Good dimensional accuracy
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Smoother cast surface finish than sand casting
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Improved mechanical properties compared to sand casting
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Thinner walls can be cast compared to sand casting
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Reverse draft internal pockets and forms can be cast in using preformed sand core inserts
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Steel pins and inserts can be cast in to the part
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Faster production times compared to other processes.
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Once the tolling is proven, the product quality is very repeatable.
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Outsourced Tooling setup costs can be lower than sand casting.
Gravity Casting Parts
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