Steps for refining coarse salt

I believe everyone has heard of coarse salt. This is a kind of salt extracted from salt water such as seawater or salt wells. Because it is not refined salt, it is called coarse salt. In people's daily lives, if you want to make further use of coarse salt and make it play a greater role, you need to refine the coarse salt. So what are the steps for refining coarse salt? Let's introduce it in detail below.

There are many soluble impurities (magnesium chloride, calcium chloride, sodium sulfate, etc.) in crude salt. In order to effectively remove magnesium chloride, calcium chloride and sodium sulfate, there are three reasonable orders for adding reagents:

1. Add NaOH first, then add barium reagent, and then add Na2CO3

2. Add barium reagent first, then NaOH, and then Na2CO3

3. Add barium reagent first, then add Na2CO3, and then add NaOH

1. Add water to dissolve the coarse salt

2. Let it settle

3. Pour the upper clear layer into the funnel for filtration

Fourth, place the filtrate in an evaporating dish and heat it to evaporate

This is a simple treatment, and the obtained salt crystals need to be further purified (the crude salt generally contains many impurity ion compounds and halogen elements or compounds).

The main component of table salt is NaCl. Crude salt refers to NaCl containing impurities. Soluble impurities are mostly magnesium chloride, calcium chloride, etc., and insoluble impurities include mud and sand.

The main operations of crude salt purification can be divided into two parts: one is filtration, the purpose of which is to separate insoluble solid impurities from NaCl, and the other is crystallization, the purpose of which is to separate NaCl from soluble impurities with steep solubility.

The purpose of weighing crude salt and purified salt before and after the experiment is to calculate the yield of crude salt.

When making a filtering device, pay attention to three key points: 1. The edge of the filter paper is lower than the edge of the funnel; 2. The tip of the funnel is close to the inner wall of the beaker; 3. Use a glass rod to drain and stick it to the three layers of filter paper.

• During the evaporation of the filtrate, stir with a glass rod to prevent the liquid from splashing due to the local overheating of the solution.

When the filtrate is almost dried up, heating should be stopped and the residual heat of the evaporating dish should be used to evaporate it. The reason for this is that if heating is continued, solid splashing will occur.