CalciumhydroxideproductionUsingseashellsandcharcoalMade by plante1999

Introduction

It is know that when calcium carbonate is heated to 850 degree Celsius it decompose to carbon dioxideand calcium oxide (1), This reaction have been use since very old time for quicklime production. Mixingthe calcium oxide with water would produce calcium hydroxide (2) which has been use as a cementsince early man civilization. A typical lime kiln was made with brick, the fuel was coal/charcoal and thecalcium carbonate was in form of limestone (the name is a little obvious). Air supply was notcompressed as modern variant; the kiln was filled with alternated layer of coal/limestone.

Material required:

Hardwood charcoal/hardwood

Good purity limestone/seashells

16 normal bricks

Hair drier

1.5 inch steel pipe by 2 feet

Glass stir rod(steel could also work)

A polypropylene container

A stainless mesh

Optional:

A stainless steel mug

A thermometer

Ammonium salt

10% Hydrochloric acid, HCl

A steel plate

Experimental:

The furnace (the lime kiln)

First a furnace is made fallowing a similar pattern as this one. It is made from normal bricks and thefurnace is made on a steel plate for a better purity of the end product. If the furnace is directly made onthe ground contamination from the dirt of the ground will occur. It is preferable to use a non-oxidizedsteel plate since rust could induce iron impurity in your product. One could argue about the fact thatiron oxidizes at high temperature but it is not a problem since the furnace atmosphere will be highlyreducing.

: The Furnace

: The hairdryer

The calcium carbonate source:

One could use limestone, which is very common. But limestone could have sulphur and iron impuritywhich does make quite a bad quality product. Also limestone could be dolomitic (contain magnesiumcarbonate in it). It is know that in early time if limestone couldn’t be found sometime seashells whereused instead. Seashells could be picked near a lake/ocean but one could buy some at the dollar store fora really low price. It is a good idea to test the seashells for calcium, dissolving one seashell in 10% HClshould make large amount of effervescence and a colorless solution, if this solution is added to a sodiumcarbonate and/or sodium sulphate solution a white precipitate should form.

CaCO3 + 2HCl -) CaCl2 + H2O + CO2

CaCl2 + Na2CO3 -) 2NaCl + CaCO3↓

CaCl2 + Na2SO4 -) 2NaCl + CaSO4 ↓

:The seashells

The fuel:

If one live in a countryside he could use wood but he would have been warned that using wood in thistype of furnace is really smelly since wood seam to char and only the carbon produced seam to burn. Abetter fuel is hardwood charcoal in large pieces. Hardwood charcoal burn with an hotter temperaturethan wood but produce a lot of carbon monoxide gas, In fact when the blower of the furnace is turnedoff large amount of blue flame is made proving that the charcoal does not burn completely to carbondioxide.

:'' If one live in a countryside he could use wood’’ (the forest near the backyard of my house)

Using the kiln:

First make a layer of charcoal on the bottom of the furnace, add a layer of seashells on top of it, onehandful of seashell is a good proportion, then add a layer of charcoal on top of the seashells. For

starting the furnace it is recommended to use some type of alcohol, like methanol (wood alcohol). Pourmost of the methanol on the bottom of the furnace and light it, when the charcoal/wood seams to burnby itself start the hairdryer to maximum speed (Check for the cold mode to reduce electricity cost). Ittakes about 10minutes to complete a run.

: ‘’A better fuel is hardwood charcoal in large pieces.’’

:The first layer of charcoal

: The layer of seashells

: The last layer of charcoal

: ‘’ It takes about 10minutes to complete a run.’’

Processing/drying:

After the run the shells will be on the bottom of the furnace. Shells are now made mostly of calciumoxide, CaO. Simply mix the shells with distill water in a polypropylene container. After a few minutes thedistilled water will become cloudy and large amount of heat will be generated, this is an indication thatyou’re on the right track. Mix the shells in the water to make a paste, the mixture will heat a lot. At thispoint one could simply purify it by his own way, the paste is made mostly of calcium hydroxide andcalcium carbonate impurity.

First pour the mixt in a Stainless steel mug and heat the mug to boil off water. Then you will end up witha powder with some shells pieces. To remove the shells pieces use a Stainless steel mesh, this willremove most of the calcium carbonate contamination. You will end up with a white powder.

: Temperature rising when the calcium oxide react with water and the newly formed calcium hydroxidepaste.

Testing:

To test the product for calcium hydroxide/calcium carbonate contamination I recommend to use thissimple procedure, it does not show the percentage of carbonate contamination but it does give a goodapproximation. First dissolve some of your crude product in dilute HCl, if it makes almost noeffervescence and a colorless solution your product doesn’t have a lot of contamination from calciumcarbonate/carbon. Then make a solution of ammonium salt and add your crude product to it, a strongodor of ammonia should be observed. For further purification one could dissolve the crude product indistilled water, filter the solution and dry it to get rid of most impurities.

Description of the crude product: Pure white powders with few small black particles which I suppose arecarbon.

:''Pure white powder with few small black particles which I suppose are carbon.''

Quote 1:CaCO3 -850degree Celsius-) CaO + CO2

Quote 2;CaO + H2O -) Ca(OH)2

Reference:

Wikipedia-calcium hydroxide-calcium oxide-lime kilnMy own work