Resource utilization method of sludge

Abstract

The invention provides a resource utilization method of sludge, and belongs to the technical field of resource utilization. The invention provides a sludge resource utilization method which comprises the following steps: carrying out first roasting on sludge to obtain gas containing phosphorus pentoxide and residues; mixing the gas containing phosphorus pentoxide with lime liquid for double decomposition reaction to obtain calcium phosphate; the calcium phosphate is used for preparing a chemical fertilizer; the residues are subjected to second roasting, organic matter is removed, and residues containing aluminum oxide and / or ferric oxide are obtained; the residues and hydrochloric acid are mixed for acid dissolution, and a solution containing aluminum chloride and / or ferric chloride is obtained; the solution containing aluminum chloride and / or ferric chloride is used for preparing polyaluminum chloride and / or polyferric chloride. According to the method, the sludge is used as a raw material to obtain calcium carbonate and the solution containing aluminum chloride and / or ferric chloride, the chemical fertilizer and polyaluminum chloride and / or polyferric chloride are further prepared, and resource utilization of the sludge is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization, and in particular to a method for resource utilization of sludge. Background Art

[0002] In general water treatment processes, in order to further remove total phosphorus and COD, a dosing sedimentation tank is often set up at the back end of the effluent. In the dosing sedimentation tank, polyaluminum chloride or polyferric chloride is added to flocculate the impurities in the water to generate sludge. The current disposal of sludge is generally landfill, incineration or brick making. However, since the sludge is rich in phosphorus and a large amount of aluminum and iron salts, it will cause secondary pollution, so there is an urgent need for a method for resource utilization of sludge. Summary of the invention

[0003] The purpose of the present invention is to provide a method for resource utilization of sludge, and the present invention realizes resource utilization of sludge.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a method for resource utilization of sludge, comprising the following steps:

[0006] The sludge is first roasted to obtain a gas containing phosphorus pentoxide and a residue;

[0007] The gas containing phosphorus pentoxide is mixed with lime liquid to carry out double decomposition reaction to obtain calcium phosphate;

[0008] The calcium phosphate is used to prepare fertilizer;

[0009] The residue is subjected to a second roasting to remove organic matter and obtain a residue containing aluminum oxide and / or iron oxide;

[0010] The residue is mixed with hydrochloric acid for acid dissolution to obtain a solution containing aluminum chloride and / or ferric chloride;

[0011] The solution containing aluminum chloride and / or ferric chloride is used to prepare polyaluminum chloride and / or polyferric chloride.

[0012] Preferably, the sludge comprises, by mass fraction, 70-80% water, 10-15% organic matter, 1-2% phosphorus, 0-2.4% polyferric chloride, and 0-2.4% polyaluminium chloride.

[0013] Preferably, the first calcination is carried out under oxygen-free conditions, the temperature of the first calcination is 420° C., and the time is 0.5 h.

[0014] Preferably, the mass concentration of the lime solution is 50%.

[0015] Preferably, the mixing of the gas containing phosphorus pentoxide with lime liquid comprises mixing the lime liquid with the gas containing phosphorus pentoxide in a spraying manner.

[0016] Preferably, the second calcination temperature is 600-800° C. and the time is 1-1.5 h.

[0017] Preferably, the ratio of the amount of aluminum oxide and / or iron oxide in the residue to the amount of HCl in the hydrochloric acid is 1:1.0-1.2;

[0018] The mass concentration of the hydrochloric acid is 25-30%.

[0019] Preferably, the acid dissolution time is 2 to 5 hours.

[0020] Preferably, the preparation of polyaluminium chloride and / or polyferric chloride comprises: subjecting a solution containing aluminium chloride and / or ferric chloride to a polymerization reaction to obtain the polyaluminium chloride and / or polyferric chloride.

[0021] Preferably, the polymerization reaction time is 24 hours.

[0022] The present invention provides a method for resource utilization of sludge, comprising the following steps: first roasting the sludge to obtain gas and residue containing phosphorus pentoxide; mixing the gas containing phosphorus pentoxide with lime liquor for double decomposition reaction to obtain calcium phosphate; the calcium phosphate is used to prepare fertilizer; second roasting the residue to remove organic matter and obtain residue containing aluminum oxide and / or iron oxide; mixing the residue with hydrochloric acid for acid dissolution to obtain a solution containing aluminum chloride and / or ferric chloride; the solution containing aluminum chloride and / or ferric chloride is used to prepare polyaluminum chloride and / or polyferric chloride. The resource utilization method of the present invention uses sludge as raw material to obtain calcium carbonate and a solution containing aluminum chloride and / or ferric chloride, and further prepares fertilizer and polyaluminum chloride and / or polyferric chloride, thereby realizing resource utilization of sludge. DETAILED DESCRIPTION

[0023] The present invention provides a method for resource utilization of sludge, comprising the following steps:

[0024] The sludge is first roasted to obtain a gas containing phosphorus pentoxide and a residue;

[0025] The gas containing phosphorus pentoxide is mixed with lime liquid to carry out double decomposition reaction to obtain calcium phosphate;

[0026] The calcium phosphate is used to prepare fertilizer;

[0027] The residue is subjected to a second roasting to remove organic matter and obtain a residue containing aluminum oxide and / or iron oxide;

[0028] The residue is mixed with hydrochloric acid for acid dissolution to obtain a solution containing aluminum chloride and / or ferric chloride;

[0029] The solution containing aluminum chloride and / or ferric chloride is used to prepare polyaluminum chloride and / or polyferric chloride.

[0030] The present invention performs a first roasting on the sludge to obtain gas containing phosphorus pentoxide and residues.

[0031] In the present invention, the sludge preferably comprises 70-80% water, more preferably 75-78% by mass fraction;

[0032] In terms of mass fraction, the sludge preferably contains 10-15% organic matter.

[0033] The sludge preferably comprises 1 to 2% phosphorus by mass fraction;

[0034] In terms of mass fraction, the sludge preferably includes 0 to 2.4% polyferric chloride;

[0035] In terms of mass fraction, the sludge preferably includes 0 to 2.4% polyaluminium chloride.

[0036] In the present invention, the shape of the sludge is preferably in block form. The present invention has no particular limitation on the method for obtaining the block sludge, and any method known to those skilled in the art may be used. Specifically, in an embodiment of the present invention, the sludge is pressed into blocks using a plate and frame filter.

[0037] In the present invention, the temperature of the first roasting is preferably 420°C, the time is preferably 0.5h, and the first roasting is preferably carried out under anaerobic conditions. During the first roasting process, phosphorus in the sludge reacts with oxygen contained in the sludge to generate phosphorus pentoxide.

[0038] At the above first roasting temperature, the organic matter in the sludge is in the initial stage of carbonization and produces a small amount of carbon dioxide.

[0039] After the gas containing phosphorus pentoxide is obtained, the present invention mixes the gas containing phosphorus pentoxide with lime liquid to carry out double decomposition reaction to obtain calcium phosphate.

[0040] In the present invention, the mixing of the gas containing phosphorus pentoxide with lime liquor comprises mixing the lime liquor with the gas containing phosphorus pentoxide in a spraying manner.

[0041] In the present invention, the mass concentration of the lime solution is preferably 50%.

[0042] After obtaining the calcium phosphate, the present invention uses the calcium phosphate to prepare fertilizer.

[0043] After obtaining the residue, the present invention performs a second roasting on the residue to remove organic matter. 并 A residue containing aluminum oxide and / or iron oxide is obtained.

[0044] In the present invention, the temperature of the second roasting is preferably 600-800°C, more preferably 700-750°C; the time is preferably 1-1.5 hours. The second roasting is preferably carried out under aerobic conditions. During the second roasting process, the COD organic matter in the sludge is carbonized, and the polyaluminum chloride and / or polyferric chloride in the sludge will generate aluminum oxide and / or iron oxide.

[0045] After obtaining the residue containing aluminum oxide and / or iron oxide, the present invention mixes the residue containing aluminum oxide and / or iron oxide with hydrochloric acid for acid dissolution to obtain a solution containing aluminum chloride and / or iron chloride.

[0046] In the present invention, the ratio of the amount of aluminum oxide and / or iron oxide in the residue to the amount of HCl in the hydrochloric acid is preferably 1:1.0-1.2; the mass concentration of the hydrochloric acid is preferably 25-30%.

[0047] In the present invention, the acid dissolution time is preferably 2 to 5 hours, more preferably 3 to 4 hours.

[0048] After obtaining the solution containing aluminum chloride and / or ferric chloride, the present invention uses the solution containing aluminum chloride and / or ferric chloride to prepare polyaluminum chloride and / or polyferric chloride.

[0049] In the present invention, the solution containing aluminum chloride and / or ferric chloride is preferably subjected to a polymerization reaction to obtain the polyaluminum chloride and / or polyferric chloride.

[0050] In the present invention, before the polymerization reaction, the pH value of the solution containing aluminum chloride and / or ferric chloride is preferably adjusted to 3.5.

[0051] In the present invention, the pH adjuster for adjusting the pH value is preferably CaO.

[0052] In the present invention, the polymerization reaction time is preferably 24 hours.

[0053] The method for resource utilization of sludge provided by the present invention is described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] By mass fraction, the sludge includes 78% water, 13% organic matter, 1% phosphorus, 2% polyferric chloride, and 1.8% polyaluminium chloride.

[0056] The sludge is placed in a first calcining furnace and first calcined at 420°C for 0.5 h, and then first calcined at 700°C for 1.2 h to obtain a gas containing phosphorus pentoxide and a residue;

[0057] The exhaust port of the roasting furnace is provided with a lime solution (mass concentration of 50%) for spraying to perform double decomposition reaction to obtain calcium phosphate; the calcium phosphate is prepared into fertilizer;

[0058] After the first roasting is completed, the temperature is raised to 700°C and air is introduced for oxidation. After the carbonized organic matter is roasted, carbon dioxide is produced and the spray is turned off. After 1 hour, a residue rich in aluminum oxide and iron oxide is left, completing the second roasting.

[0059] The residue is mixed with hydrochloric acid having a mass concentration of 30% (the ratio of the amount of aluminum oxide and / or iron oxide in the residue to the amount of HCl in the hydrochloric acid is 1:1.2) and acid-dissolved for 180 minutes to obtain a solution containing aluminum chloride and / or iron chloride;

[0060] The solution containing aluminum chloride and / or ferric chloride is adjusted to pH 3.5 with CaO, and then subjected to a polymerization reaction for 24 hours to obtain polyaluminum chloride and / or polyferric chloride.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for resource utilization of sludge, characterized in that: The following steps are involved: The sludge is first roasted to obtain a gas containing phosphorus pentoxide and a residue; The gas containing phosphorus pentoxide is mixed with lime liquid to carry out double decomposition reaction to obtain calcium phosphate; The calcium phosphate is used to prepare fertilizer; The residue is subjected to a second roasting to remove organic matter and obtain a residue containing aluminum oxide and / or iron oxide; The residue is mixed with hydrochloric acid for acid dissolution to obtain a solution containing aluminum chloride and / or ferric chloride; The solution containing aluminum chloride and / or ferric chloride is used to prepare polyaluminum chloride and / or polyferric chloride.

2. The resource utilization method according to claim 1, characterized in that: Calculated by mass fraction, the sludge includes 70-80% water, 10-15% organic matter, 1-2% phosphorus, 0-2.4% polyferric chloride and 0-2.4% polyaluminium chloride.

3. The resource utilization method according to claim 1, characterized in that: The first calcination is performed under oxygen-free conditions, with a temperature of 420° C. and a time of 0.5 h.

4. The resource utilization method according to claim 1, characterized in that: The mass concentration of the lime solution is 50%.

5. The resource utilization method according to claim 1, characterized in that: The mixing of the gas containing phosphorus pentoxide with lime liquid includes mixing the lime liquid with the gas containing phosphorus pentoxide in a spraying manner.

6. The resource utilization method according to claim 1, characterized in that: The second calcination is carried out at a temperature of 600 to 800° C. and for a time of 1 to 1.5 hours.

7. The resource utilization method according to claim 1, characterized in that: The ratio of the amount of aluminum oxide and / or iron oxide in the residue to the amount of HCl in the hydrochloric acid is 1:1.0-1.2; The mass concentration of the hydrochloric acid is 25-30%.

8. The resource utilization method according to claim 1 or 7, characterized in that: The acid dissolution time is 2 to 5 hours.

9. The resource utilization method according to claim 1, characterized in that: The preparation of polyaluminium chloride and / or polyferric chloride comprises: subjecting a solution containing aluminium chloride and / or ferric chloride to a polymerization reaction to obtain the polyaluminium chloride and / or polyferric chloride.

10. The resource utilization method according to claim 9, characterized in that: The polymerization reaction time is 24 hours.