Calcium hydroxide is difficult to handle. However, it is used on larger systems because lime is economical and sometimes for remineralization on desalination systems.
The type of feed systems varies with the size of the application which you have not stated. Hydrated lime is more commonly used because it is easier to handle than quicklime.
Here is a simplified description. On large systems, bulk hydrated lime is stored in a silo. The dry material is metered out into an agitated slurry tank to make a slurry of about 20% lime. This slurry tank is located directly below the silo.
This slurry is then diluted to approximaely 10-15% hydrated lime solution in an agitated application tank. The slurry is pumped from the application tank to the application point where it is mixed into the water flow.
The temperature of the water is only important in the need for freeze protection.
I am not sure what your application is but I can give you my expereince in the municipcal water treatment field. I have installed 3 Stanco bulk storage silos in my career. In order to size the amount of hydrated lime (calcium hydroxide) you will have to figure out how much lime you will be using on a daily basis to achieve the pH increase you are looking for. From there you will be able to determine if you need to go with bulk silo storage or a small bagged type of system. Any system that you put in will requrie some type of rotary valve upstream of the screw feed device. Without the rotary valve you can potenitally flood the system with an uncontrolled movement of hyrated lime material.
A typical arrangement is to meter the lime into a mixing tank and dilute it with a constant volume of water. One then pumps it out of the mixing tank to the application point. This is much simpler. If you can, arrange it so that instead of using a pump have the slurry overflow the mixing tank and flow by gravity to the application point. Nothing is simpler than gravity. Anybody that has worked with lime will know that there is constant maintenace required on the pump and the piping. You will get calcium carbonate depostion on the interanl walls. Eventually you have to break it off or the pipe will plug solid. Therefore use rubber hose as opposed to solid pipe. With rubber hose you can "massage" the pipe and the calcium carbonate build up on the inner walls will crack off.
My other recommendation is to get a bag of hydrated lime and make some slurry yourself. do all the different concentratons you want on it. Nothing better than to see and get a feel for what you are handling. Also go visit some installations
1. Pnuematically convey the hydrated lime from the main storage tank to the augering hopper/auger/mixing tank
2. Locate the augering hopper/auger/mixing tank over the process application point
3. The auger then flow paces and meters the lime into the mixing tank. The mixing tank is fed a constant flow of mixing water. Therefore the pH of the slurry will change if there is a change in process flow. The mixed slurry overflows into the process by gravity. Nothing simpler than that. Almost zero maintenance
