GB2142840A

GB2142840A - Milling in the presence of a surface active agent additive

Info

Publication number: GB2142840A
Application number: GB08413171A
Authority: GB
Inventors: Eva Szekely; Roza Szekely
Original assignee: Magyar Szenhidrogenipari Kutatofejleszto Intezet
Current assignee: Magyar Szenhidrogenipari Kutatofejleszto Intezet
Priority date: 1983-05-24
Filing date: 1984-05-23
Publication date: 1985-01-30
Also published as: GB2142840B; HUT34378A; DE3416245C2; HU199316B; DE3416245A1; AT390213B; SU1402247A3; ATA170284A; GB8413171D0

Abstract

The additive may comprise sodium alkylsulphonate or sodium alkylbenzenesulphonate, and may also include ethylene oxide, an ester, an alkylsulphate, an alkylbenzimdazolesulphonate, or triethanolamine. The additive may further comprise a potassium or sodium sulphate or phosphate salt in solution.

Description

SPECIFICATION Milling This invention relates to a process for intensifying the milling of natural minerals as well as of artificial, mineral-like products.

The process of milling-disintegrating becomes needed for establishing the appropriate particle size and particle size distribution in the course of the use of further processing of various minerals, e.g. of coal, ores, bauxite, pearlite, tuff, dolomite, clay or of other man-made products, e.g. porcelain flour, slag, fly ash and ceramic semi-products.

The requirement against the product may be uniform in the various industrial sectors in spite of the milling machines operating by different principles and in spite of the various rough materials. Thus, the modification of them can also be possible by a uniform process.

In the Hungarian Patent No. 155,524 a process is disclosed using a milling auxiliary material, in an amount of 0.001 to 1 per cent (weight by weight) as calculated for the material to be milled. This adjuvant is a phosphate compound containing organic nitrogen. The use of this additive results in a surplus of 1 7 per cent in the finer fraction of the milled limestone flour.

According to the same patent specification, an increase by 50 per cent in the milling capacity is reached by using an additive consisting of urea and sesquiphosphate-triethanolamide components for milling cement clinker.

In the DE-PS Patent No. 2,251,935 the use of aliphatic acetate esters as a milling additive is suggested for the dry milling of minerals, particularly of pigments and fillers.

The process of our invention is not connected to any unique rough material or milling equipment type. This process means a development from an economical point of view as compared to those known at present for the following reasons.

1) The particle size and its distribution are achieved with savings in energy consumption; 2) The efficiency of milling is improved; 3) The capacity of the milling equipment is enhanced.

Our invention is based on the discovery that the milling process can be intensified by using an anionic and/or non-ionic surface active agent as milling additive in the course of milling. As surface active agent, at least one alkylsulphonate and/or alkylbenzenesulphonate and/or petroleumsulphonate and/or ethylene oxide adduct and/or fatty acid ester of polyvalent alcohols and/or alkylsulphate and/or alkylbenzimidazolesulphonate and/or triethanolamine are used in an amount of 0.001 to 1 per cent (weight by weight) as calculated for the weight of the material to be milled. Suitably, the milling additive is applied to the material to be milled in the form of a spray of an aqueous solution of 2 to 20 per cent (weight by weight) concentration.

The auxiliary materials in milling may contain 1 to 50 per cent (weight by weight) of potassium and/or sodium sulphate or chloride or phosphate.

The process of our invention can also be used for milling coals in thermal power-stations.

The process of our invention will be illustrated by the following Examples without, however, any limitation thereto.

Example 1 When 0.1 kg of coal was milled in a laboratory ball mill [volume (V) = 0.35 litre; n = 16 rpm; weighty,,, = 0.3 kg] an adhesion phenomenon occurred both on the internal surface of the mill body as well as on the balls. When the same experiment was carried out with a coal containing 0.05 per cent (weight by weight) of a sodium alkylsulphonate and 30 per cent (weight by weight) of sodium sulphate and 10 per cent (weight by weight) of sodium chloride as calculated on the weight of the sodium alkysulphonate, no adhesion was observed either on the surface of the balls or on the internal wall of the mill body. Particle size distribution for milling mixtures with and without additives are given in Table 1.

Table 1 Particle size d is t r ibut i o n < 63 > 63 > 80 > 200 ,L000 ,L500 2000 /um Non treated 1.95 L.22 7.84 41.2 6.0 38.9 2.77 (%) Treated () 2.23 L.52 6.03 41.L 5.9 41.3 1.86 The surplus in the fine fraction, related to the fraction < 63 m was 1 5 per cent.

Example 2 When carrying out the experiment in a laboratory ball mill (V = 0.35 litre, ratio of the coal to the balls = 1:1 and 1:3, respectively) an adhesion was observed in both cases both on the internal wall of the mill body as well as on the balls. The amount of the freely moving grist was diminished with the decrease in the ball ratio, when an identical milling time was considered.

No adhesion was observed, when the experiment was repeated with a milling additive containing 0.1 per cent (weight by weight) of a sodium alkylbenzenesulphonate, as well as 20 per cent (weight by weight) of sodium sulphate and 10 per cent (weight by weight) of trisodium phosphate as calculated the weight of the sodium alkylbenzenesulphonate.

The surplus in the fine fraction, related to the fraction < 63,um using an 1:1 ratio of the coal to the balls (n = 1 6 rpm) was 1 5 per cent, while by using an 1:3 ratio of the coal to the balls (n = 16 rpm) was 29 per cent.

The results of the sieving analysis are plotted on Fig. 1.

Example 3 An aqueous solution of 10 per cent of the milling additive was sprayed on the coal transported by the belt conveyor in the milling equipment of a thermal power-station. The milling additive contained 0.07 per cent (weight by weight) of a sodium alkylbenzenesulphonate as well as 0.03 per cent (weight by weight) of sodium sulphate calculated for the weight of the coal to be milled.

The surplus in the fine fraction, related to the fraction < 74,um was 1 6 per cent.

Example 4 Limestone breeze was milled in a laboratory ball mill (V = 0.35 litre, n = 16 rpm) with an 1:1 ratio of the limestone to the balls. The excess amount of the finest fraction (Gt-Go) related to the amount obtained in the reference experiment (Go) are plotted as percent in the function of the milling time (t) in Fig. 2. The use of a milling additive containing 0.005 per cent (weight by weight) of a petroleumsulphonate calculated for the weight of the material to be milled resulted in a surplus of Gt-Go 1 3 per cent.

Go Example 5 Bauxite was milled in a laboratory ball mill (V = 0.35 litre, n = 16 rpm) with an 1:1 ratio of the bauxite to the balls. The milling additive contained 0.5 per cent of triethanolamine calculated for the weight of the material to be milled. The specific surface of the ground material was controlled by Blaine's method during the milling process in every half hour.

The measured data were: Milling time Specific surface (h) (cm2/g 0.5 4350 1.0 5820 1.5 6250 9 per cent surplus for < 80,um was calculated.

Example 6 Barium sulphate was milled in a laboratory ball mill (V = 0.35 litre, n = 16 rpm) with an 1:1 ratio of the barium sulphate to the balls. The milling additive contained 0.1 per cent (weight by weight) of an alkylsulphate and 0.05 per cent (weight by weight) of potassium sulphate calculated for the weight of the material to be milled. The specific surface of the ground material was controlled by Blaine's method during the milling process in every half hour. The measured data were: Milling time Specific surface (h) (cm2/g) 0.5 4370 1.0 5720 1.5 6140 11 per cent surplus for < 80,um fraction was calculated.

Example 7 Pearlite was milled in a laboratory ball mill (V = 0.35 litre, n = 1 6 rpm) with an 1:1 ratio of the pearlite to the balls. The milling additive contained 0.01 per cent (weight by weight) of a petroleumsulphonate and 0.08 per cent (weight by weight) of lauryl alcohol polyethyleneglycol ether calculated for the weight of the material to be milled.

The results in the fine fraction, related to the fraction < 80,um was 14 per cent. The saving in energy related to the reference sample was 1 5 per cent.

Example 8 Dolimite was milled in a laboratory ball mill (V = 0.35 litre, n = 16 rpm) with an 1:1 ratio of the dolomite to the balls. The milling additive contained 0.2 per cent (weight by weight) of an alkylbenzimidazolesulphonate calculated for the weight of the material to be milled.

The specific surface of the ground material was controlled by Blaine's method during the milling process in every half hour. The measured data were: Milling time Specific surface (h) (cm2/g) 0.5 3220 1.0 4140 1.5 4520 8 per cent surplus for < 80,um was calculated.

Claims

1. A process for intensifying the milling of natural minerals and of artificial mineral-like products, which comprises spraying as milling additive at least one alkylsulphonate and/or alkylbenzenesulphonate and/or petroleumsulphonate and/or ethylene oxide adduct and/or fatty acid ester of polyvalent alcohols and/or alkylsulphate and/or alkylbenzimidazolesulphonate and/or triethanolamine in an amount of 0.001 to 1 per cent (weight by weight) as calculated for the weight of the material to be milled in an aqueous solution of 2 to 20 per cent (weight by weight).

2. The process as claimed in claim 1, which comprises dissolving potassium and/or sodium sulphate or their chloride of phosphate salts in an amount of 1 to 50 per cent (weight by weight) as calculated for the milling additive in an aqueous solution of the milling additive.

3. A process which comprises milling a natural or synthetic grist in the presence of an anionic and/or non-ionic surfactant.

4. A process substantially as hereinbefore described in any one of Examples 1 to 8.